JP2019131740A - Heat storage material - Google Patents

Abstract

To provide a heat storage material excellent in heat accumulation performance per unit volume, wear resistance, and compression strength.SOLUTION: A heat storage material is composed of granular synthetic zeolite, which is one selected from A type synthetic zeolite, X type synthetic zeolite, and Y type synthetic zeolite, or a mixture of two or more of them, and the synthetic zeolite at least having a first particle size distribution peak and a second particle size distribution peak.SELECTED DRAWING: None

Description

  INDUSTRIAL APPLICABILITY The present invention is used in a heat storage device that repeatedly performs an adsorption operation that adsorbs adsorbate and releases heat of adsorption and a desorption operation that desorbs the adsorbate by external heat, such as an adsorption heat pump, and is used for heat generation and cooling. It relates to heat storage materials.

  Conventionally, a heat storage device represented by an adsorption heat pump is one of the best exhaust heat recovery and regeneration methods that can be operated using low-quality heat energy as a heat source without using auxiliary power. It is considered a strong candidate. In this process of operation, to regenerate the adsorbate, eg, the adsorbent that has adsorbed water, the adsorbent is heated to desorb the adsorbate, and the dried adsorbent is cooled to the temperature used for adsorbate adsorption. And again used for adsorbate adsorption.

As an adsorbent for this type of adsorption heat pump, adsorbate such as water and water vapor is adsorbed at low temperature, and adsorbate adsorbed by heating is desorbed. For example, zeolite, activated carbon, silica gel, alumina can be used repeatedly. Etc. are widely known. Among them, zeolite has a highly polar cation moiety in its structure, so it retains adsorption performance even at low humidity of 10% or less compared to other adsorbents. It is used for.
In order to perform adsorption and desorption repeatedly, an adsorbent that adsorbs a large amount of adsorbate at the time of adsorption and desorbs the adsorbate adsorbed at the lowest possible temperature at the time of desorption is often used. Various studies have been made on materials.

Non-Patent Document 1 discloses a technology that collects low-quality energy discarded in large quantities, converts it into high-quality heat, and regenerates it, not only saving energy, saving resources, and reducing greenhouse gases, but also utilizing unused energy. As a key technology, there are two types of heat pumps that can be used repeatedly: mechanical compression and chemical reaction. And six problems are mentioned about adsorption | suction and the chemical heat pump by a chemical reaction of gas and solid. As one of them, since it is used as a particle layer filled with solid particles, it is necessary to secure a gas flow path, the effective thermal conductivity of the particle layer is low, and the amount of particles is increased to improve the heat output performance. Is listed as essential.
On the other hand, Non-Patent Document 2 relates to the development of a steam regenerative heat pump system for effective utilization of low-temperature exhaust heat to heat the amount of saturated steam generated by direct contact between zeolite and hot waste water and the dry air used for zeolite regeneration. Estimate the amount of hot wastewater required for the heat, estimate the mass of the hot wastewater and generated steam per cycle, and the amount of heat. When the wastewater temperature is 80 ° C and the steam temperature is 140 ° C, the mass ratio is about 0.038. It is about 0.57, and describes that further improvement in efficiency can be expected if exhaust gas having a high temperature can be used in the desorption process.
Furthermore, Non-Patent Document 3 describes magnesium-exchanged A-type zeolite as a heat pump heat storage material, and synthesizes A-type zeolite with an Mg exchange rate of 89% for Mg-exchanged A-type zeolite as a zeolite-water heat pump heat storage material. Then, the heat of water vapor hydration was measured, and the maximum heat storage amount at a dehydration level of 200 ° C. was obtained, ¹ MJkg ⁻¹ , and this value is a heat storage material that can be used repeatedly even in the heat storage density of the zeolite-water system. It is described that it is a high level comparable to the heat storage density of the latest alkaline ion battery.

In Patent Document 1, in the water vapor adsorption isotherm measured at 25 ° C., when the relative vapor pressure changes by 0.15 in the range of the relative vapor pressure of 0.05 or more and 0.30 or less, the change in the adsorption amount of water is 0. An adsorption heat pump having a relative vapor pressure range of 18 g / g or more and having a skeleton structure containing aluminum, phosphorus, and heteroatoms as an adsorbent has been proposed, and the amount of moisture adsorbed by adsorption / desorption of the adsorbent It is described that the adsorption heat pump can be driven efficiently by using a low-temperature heat source as compared with the prior art because the adsorbent can be regenerated (desorbed) at a low temperature.
In Patent Document 2, as in Patent Document 1, adsorbate can be adsorbed and desorbed in a low relative vapor pressure region, the low temperature side is relatively high temperature, the high temperature side is relatively low, and the temperature difference between them is As an adsorbent capable of operating an adsorption heat pump sufficiently even under small conditions, it is disclosed that an AFI-type zeolite having tin and / or titanium in a predetermined ratio in addition to aluminum, phosphorus and iron in the skeleton structure is useful. Has been.
On the other hand, Patent Document 3 includes mesopores and micropores as materials capable of sufficiently adsorbing water vapor on the high humidity side, and the water vapor adsorption amount ratio shown in the following formula (1) is 1.8 or more. Some porous carbon has been proposed.
Water vapor adsorption amount ratio = water vapor adsorption amount when the relative humidity is 90% / water vapor adsorption amount when the relative humidity is 70% (1)

Patent Document 4 proposes a heat storage material containing zeolite chemically bonded to carbon nanofibers and a method for producing the same, and has low thermal resistance between the zeolite and carbon nanofibers and uniformly disperses the carbon nanofibers. It is easy to form and a network of percolated carbon nanofibers is easily formed, so heat is easily transmitted through the carbon nanofibers, so the heat storage material has high thermal conductivity and heat is quickly transmitted to the details, so it is efficient. It is said that heat can be exchanged.
Furthermore, in Patent Document 5, in order to realize an adsorption heat pump with a small amount of adsorption in a region where the relative vapor pressure is low and a high energy recovery rate, as an adsorbent, activated carbon and at least inside the pores of the activated carbon, An adsorbent for an adsorption heat pump characterized by having an organic molecule having one hydrophilic functional group and at least one nitrogen-containing heterocycle has been proposed.

JP 2008-267802 A JP 2012-67002 A Japanese Patent Laying-Open No. 2015-51891 JP2015-108086A JP 2015-112563 A

Chemical Industry Co., Ltd. Published on October 30, 2010 “Future built with energy technology that can be implemented-Heavy energy roadmap 2-”, p223-227 Journal of Japan Society of Energy and Resources, Vol.32, No.5pp.9-16 (Date received: August 2, 2011) Resources and Materials VOL.117 p.875-879 (accepted on September 17, 2001)

An adsorption heat pump is obtained by an adsorption operation that adsorbs adsorbate to the adsorbent while releasing heat of adsorption, and a desorption operation that desorbs the adsorbate from the adsorbent by external heat, and by evaporation of the adsorbate. The generated cold heat is taken out to the outside, the generated adsorbate vapor is collected in the adsorber, the adsorbate vapor desorbed by the adsorber is condensed by the external cold heat, and the condensed adsorbate is removed. It has a condenser that feeds the evaporator. In the adsorption heat pump, the larger the amount of adsorption, the better, but the smaller the weight and volume of the adsorbent, from the viewpoint of space saving and cost reduction. Further, it is preferable from the viewpoint of increasing the amount of adsorption that the adsorber can be filled more with the limited volume of the adsorber.
However, in the above-described prior art, various studies have been made to improve the adsorption performance of the adsorbent itself, but the configuration of the adsorbent that can be highly filled in the adsorber has not been studied.
It is an object of the present invention to provide a heat storage material that can be filled more than the limited volume of a heat storage device and that is excellent in heat storage performance, wear resistance, and compressive strength per unit volume.
In the present specification, the “heat storage material” is defined to mean a case where the “adsorption material” is used in a heat generation / cooling system for the purpose of heat storage.

  As a result of intensive studies to solve the above-described conventional problems, the inventors of the present invention are one type or a mixture of two or more types selected from A-type synthetic zeolite, X-type synthetic zeolite, and Y-type synthetic zeolite, and have a particle size distribution. The present inventors have found that a heat storage material having a high heat storage performance can be obtained by producing a heat storage material obtained by mixing a plurality of heat storage materials having different peaks.

The gist of the present invention is the following [1] to [6].
[1] A heat storage material composed of granular synthetic zeolite, which is one or a mixture of two or more selected from A-type synthetic zeolite, X-type synthetic zeolite, and Y-type synthetic zeolite, A heat storage material having at least a first particle size distribution peak and a second particle size distribution peak.
[2] The peak position of the first particle size distribution peak of the synthetic zeolite is 0.25 mm or more and less than 1.5 mm, and the peak position of the second particle size distribution peak is 1.5 mm or more and 5 mm or less. 1].
[3] The heat storage material according to [1] or [2], wherein 10% or more of the number of cations capable of ion exchange in the synthetic zeolite are divalent metal ions.
[4] The heat storage material according to [1] to [3], wherein 40% or more of the number of cations capable of ion exchange in the synthetic zeolite is at least one selected from magnesium ions, cobalt ions, and calcium ions.
[5] The heat storage material according to any one of [1] to [4], wherein a bulk density in a saturated moisture adsorption state is 1040 g / L or more.
[6] The heat storage material according to any one of [1] to [5], wherein a moisture adsorption amount per unit volume is 193 g / L or more.

  According to the present invention, since the heat storage performance is high, it is possible to provide a granular heat storage material suitable for a heat storage device that increases the heat storage capacity per unit volume and is excellent in wear resistance and compressive strength.

FIG. 1 is a graph with the horizontal axis representing the content of synthetic zeolite 4A 16 × 30 and the vertical axis representing bulk density in the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2. FIG. 2 is a graph with the horizontal axis representing the content of synthetic zeolite 4A 16 × 30 and the vertical axis representing the amount of wear reduction in the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2. FIG. 3 is a graph with the horizontal axis representing the content of synthetic zeolite 4A 16 × 30 and the vertical axis representing the adsorption capacity per unit volume (L) in the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2. is there. FIG. 4 shows the heat storage materials of Examples 2, 4, 5, 6, 7 and Comparative Examples 1 and 2, with the content of synthetic zeolite 4A 16 × 30 as the horizontal axis and the exothermic temperature per unit weight as the vertical axis. It is a graph.

[Heat storage material]
The heat storage material of the present invention is a heat storage material composed of granular synthetic zeolite, which is one type selected from A-type synthetic zeolite, X-type synthetic zeolite, and Y-type synthetic zeolite, or a mixture of two or more types, and In addition, the synthetic zeolite is a granular heat storage material used in a heat storage device having at least a first particle size distribution peak and a second particle size distribution peak. Hereinafter, the heat storage material of the present invention will be described in detail.

(Zeolite)
Hereinafter, the synthetic zeolite used for the heat storage material of the present invention will be described.
Zeolite has a structure of condensed acid of silicate, and the basic unit thereof is a SiO 4 tetrahedron having _four oxygens (O) formed with silicon (Si) as the center, and this structure. SiO ₄ tetrahedron is an AlO ₄ tetrahedron in which aluminum (Al) is substituted in place of silicon, and these and other various basic structural units are combined in three dimensions, and innumerable fine channels (passages) A cage (cavity) is formed. These channels and cages exhibit various properties such as molecular adsorption and ion exchange.
The unit cell composition of zeolite can be expressed as the following formula (1), where monovalent and divalent cations are represented by M ⁺ and M ²⁺ , respectively.

(M ⁺ , M ²⁺ _1/2 ) _m [Al _m Si _n O _{2 (m + n)} ] · xH ₂ O (1)
M ⁺ = Li ⁺ , Na ⁺ , K ⁺ , Ag ⁺ , Rb ⁺ etc. M ²⁺ = Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ etc. (where m and n are integers and n ≧ m and x is a number of 0 or more.)
The number of cations capable of ion exchange in the unit cell composition of zeolite corresponds to (M ⁺ , M ²⁺ _1/2 ) _m in the above-described formula (1). For example, as a unit cell composition, NaA type zeolite is expressed as Na ₁₂ (Al ₁₂ Si ₁₂ O ₄₈ ) · 27H ₂ O, and NaX type zeolite is Na ₈₆ (Al ₈₆ Si ₁₀₆ O ₃₈₄ ) · 264H _2. O.

Synthetic zeolites are classified as A-type, X-type, Y-type, etc., depending on the SiO ₂ / Al ₂ O ₃ ratio and the difference in crystal structure. In addition, some or all of monovalent and divalent cations can be reversibly ion-exchanged with other cations. Type A zeolite containing calcium (Ca) alone or mainly containing calcium is called CaA type, and type A zeolite containing sodium (Na) alone or mainly containing sodium is called NaA type.
ZSM-5 is a high-silica-pentacil-type synthetic zeolite having a ten-membered ring developed by Mobil Oil (USA), and its analogs include ZSM-11, silicalite, silicalite-2, Pentasil type metallosilicates are known.
The unit cell composition of ZSM-5 is represented by the following formula (2)
Na _n (Al _n Si _96-n O ₁₉₂ ) · 16H ₂ O (n <27) (2)
Can be expressed as
The heat storage material of the present invention is one or a mixture of two or more selected from A-type synthetic zeolite, X-type synthetic zeolite, and Y-type synthetic zeolite, and has at least two particle size distributions described below.

That is, the heat storage material of the present invention has at least a first particle size distribution peak and a second particle size distribution peak. In addition, the peak position of the first particle size distribution peak exists on the lower particle size side than the second particle size distribution peak position.
Preferably, the peak position of the first particle size distribution peak is from 0.25 mm to 1.5 mm, the peak position of the second particle size distribution peak is from 1.5 mm to 5 mm, more preferably, the first The peak position of the particle size distribution peak is 0.45 mm or more and 1.3 mm or less, the peak position of the second particle size distribution peak is 1.5 mm or more and 3.5 mm or less, and more preferably, the first particle size distribution peak The peak position is 0.45 mm or more and 1.0 mm or less, and the peak position of the second particle size distribution peak is 1.5 mm or more and 2.5 mm or less. When the peak position of the first particle size distribution peak is 0.25 mm or more and 1.5 mm or less and the peak position of the second particle size distribution peak is 1.5 mm or more and 5 mm or less, when the heat storage material is used, the heat storage material Can be filled with high density. Thereby, when a heat storage material is used, it becomes difficult to produce the movement of the heat storage material which rubs between the particles of the heat storage material. Note that the heat storage material of the present invention preferably has at least two particle size distribution peaks, ie, a first particle size distribution peak and a second particle size distribution peak, and may have two particle size distribution peaks. It may have more than one particle size distribution peak. In addition, the particle size distribution peak is, for example, a peak size of the particle size distribution peak that is larger than the upper and lower sieves in the fraction of the heat storage material screened with the JIS standard sieve used in the following examples. can do. However, when the peak position of the first particle size distribution peak is less than 0.25 mm, it is difficult to produce industrially stabilized, and when the peak position of the second particle size distribution peak is larger than 5 mm, the empty wall at the time of filling The rate is high and the thermal efficiency is poor.

  Synthetic zeolite having particle size distribution peaks at a plurality of different peak positions can be used for the heat storage material of the present invention. As a result, the heat storage material of the present invention is filled with high density, and it is difficult for the heat storage material to rub between the particles of the heat storage material, and the cross-sectional area of the heat storage material in an arbitrary cross section increases, thereby increasing the pressure from the outside. Since the load is distributed, the load on one heat storage material is reduced. As a result, the moisture adsorption capacity per unit volume of the heat storage material is increased, and the wear resistance and compressive strength are improved.

In addition, the composition of the zeolite can reversibly ion exchange part or all of the monovalent and divalent cations with other cations.
The synthetic zeolite used in the present invention can make divalent metal ions 10% or more of the number of cations that can be ion-exchanged. In the synthetic zeolite, if 10% or more of the ion-exchangeable cations is a divalent metal ion, it is preferable from the viewpoint of moisture adsorption performance, more preferably 20% or more, and further preferably 30% or more.
Examples of divalent metal ions include magnesium ions, nickel ions, cobalt ions, zinc ions, manganese ions, and calcium ions.

  The synthetic zeolite used in the heat storage material of the present invention is at least one selected from magnesium ions, cobalt ions, and calcium ions as divalent metal ions, with 40% or more of the number of cations capable of ion exchange in the synthetic zeolite. be able to. By selecting such a zeolite, when the adsorbate is water or water vapor, the heat storage performance can be particularly improved.

[Preparation method of heat storage material]
(Step of exchanging ion-exchangeable cations in zeolite with divalent metal ions)
In the production method for obtaining the heat storage material of the present invention, a step of exchanging ion-exchangeable cations in the zeolite with divalent metal ions is required. Examples of the ion-exchangeable cation in the zeolite include at least one cation selected from alkali metal ions and alkaline earth metal ions.
In the present invention, 10% or more, preferably 30% or more, more preferably 40% or more of the number of cations capable of ion exchange are exchanged for divalent metal ions. Examples of the divalent metal ion source include at least one water-soluble compound selected from, for example, halide salts, carbonates, hydroxides, metal complex compounds, and the like, and chlorides are particularly preferable. The compound serving as the ion source may be charged as a solid into the zeolite suspension, but is preferably charged as a solution in order to improve dispersibility and reaction rate. The solvent is not particularly limited, but it is particularly preferably added as an aqueous solution in consideration of the solubility of the ion source, the influence of the ion exchange reaction on the reaction, and the like. As the divalent metal chloride, it is preferable to use magnesium chloride, cobalt chloride, nickel chloride, or zinc chloride.

In the present invention, as described above, 10% or more, preferably 30% or more, more preferably 40% or more of the number of ion-exchangeable cations in the zeolite is exchanged for divalent metal ions. May be ion-exchanged by adding the water-soluble divalent metal ion-containing compound as it is to the zeolite suspension prepared as described above, or the zeolite suspension and the water-soluble 2 Ion exchange may be performed by contacting with an aqueous solution containing a valent metal compound.
The reaction temperature for ion exchange is not particularly limited, but is usually about 0 to 200 ° C., preferably 20 to 100 ° C. The reaction time depends on factors such as the reaction temperature and cannot be determined in general. However, usually about 10 to 120 minutes is sufficient.

  The zeolite exchanged for divalent metal ions in this way is solid-liquid separated by a conventionally known means, and then sufficiently washed with water or hot water, and then at a temperature of about 100 to 800 ° C. for about 30 to 180 minutes. By performing the drying treatment, a divalent metal ion exchanged zeolite used as the heat storage material of the present invention can be obtained.

(Measurement of exchange rate of ion-exchangeable cations to divalent metal ions)
The exchange rate of ion-exchangeable cations to divalent metal ions can be determined by measuring the amount of the divalent metal cation by XRF (fluorescence X-ray measurement device) or ICP (emission analysis device). And can be calculated.

(Granulation of heat storage material)
The heat storage material of the present invention is a granular heat storage material. The heat storage material of the present invention is produced by, for example, a rolling granulation method. Specifically, for example, the heat storage material of the present invention can be produced as follows. After adding water and a binder to the raw material, the mixture is kneaded using a kneader and charged into a rolling granulator to make it spherical. Thereafter, the obtained spherical product is dried and fired to obtain the heat storage material of the present invention.
If this granulation method is used, the particle diameter of the granulated product can be easily controlled, and a granulated product having a relatively uniform shape and particle diameter can be produced. Therefore, it is possible to produce a heat storage material having particle size distribution peaks at a plurality of different peak positions by producing two or more types of granulated products having different particle sizes by a granulation method and mixing them.

The heat storage material of the present invention is produced by mixing a heat storage material having a first particle size distribution peak and a heat storage material having a second particle size distribution peak. That is, the heat storage material of the present invention includes a first heat storage material having a first particle size distribution peak and a second heat storage material having a second particle size distribution peak.
Thereby, when a heat storage material is used for a heat storage apparatus like a heat pump, for example, a heat storage material can be filled with high density. From the viewpoint of filling the heat storage material at a higher density, the mass ratio of the first heat storage material having the first particle size distribution peak and the second heat storage material having the second particle size distribution peak (first heat storage material). : Second heat storage material) is preferably 5:95 to 95: 5, more preferably 10:90 to 90:10, still more preferably 20:80 to 80:20, and even more preferably. It is 30: 70-70: 30, More preferably, it is 30: 70-50: 50.

  The bulk density in the saturated moisture adsorption state in the heat storage material of the present invention is preferably 1040 g / L or more, more preferably 1050 g / L or more, further preferably 1070 g / L or more, and further preferably 1090 g / L. L or more. When the bulk density in the saturated moisture adsorption state of the heat storage material of the present invention is 1000 g / L or more, when the heat storage material is used in a heat storage device such as a heat pump, the particles of the heat storage material are not affected by external vibration. It is hard to move and can be filled with the heat storage material at high density. In addition, the measuring method of the bulk density in the saturated moisture adsorption state will be described in detail in Examples described later. Moreover, in the Example mentioned later, although the maximum value of the bulk density in a saturated water | moisture-content adsorption | suction state is 1096 g / L, in the heat storage material of this invention, the value can be enlarged further.

  The moisture adsorption capacity per unit volume in the heat storage material of the present invention is preferably 193 g / L or more, more preferably 195 g / L or more, further preferably 200 g / L or more, and further preferably 202 g / L. That's it. When the moisture storage capacity per unit volume in the heat storage material of the present invention is 193 g / L or more, when the heat storage material is used, a heat storage material having a smaller volume than the conventional one can adsorb the same amount of moisture. In addition, the measuring method of the water | moisture-content adsorption capacity per unit volume is demonstrated in detail by the below-mentioned Example. Moreover, in the below-mentioned Example, although the maximum value of the water | moisture-content adsorption capacity per unit volume is 204 g / L, in the heat storage material of this invention, the value can be further enlarged. In addition, as for the adsorbate in which the heat storage material of this invention is used, water, water vapor | steam, ethanol, ethylene glycol etc. are mentioned, for example.

[Heat storage device]
As an example of a heat storage device that can use the heat storage material of the present invention, the heat storage material of the present invention is a heat storage unit that constitutes at least one selected from an in-vehicle air conditioner, an adsorption steam regeneration system, and an adsorption heat pump. Mention may be made of the heat storage device used.
The heat storage device obtained by gathering and using the heat storage material of the present invention can include the heat storage material of the present invention and a bag or a cylindrical container that stores the heat storage material. As a result, even if the heat storage device receives vibration from the outside, the heat storage material included in the heat storage device wears and crushes, and the generated dust deteriorates the air permeability and liquid permeability of the cylindrical container or the like, or In addition, it is possible to suppress damage to the sliding surface of a device such as a compressor or block the pores of the expansion valve. Moreover, since the heat storage material of this invention can be filled with high density, a heat storage apparatus can be reduced in size. Thereby, a thermal storage tank (tank) can also be reduced in size.

  Examples of the bag used in the heat storage device of the present invention include a wire mesh bag and a punch metal bag having liquid permeability and air permeability. In addition, examples of the cylindrical container include those in which at least the upper and lower surfaces or the peripheral surface is a mesh material, a punch metal material, or the like.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not restrict | limited by an Example.

[Evaluation of heat storage materials of Examples and Comparative Examples]
The following evaluation was implemented with respect to the thermal storage material of an Example and a comparative example.

(Bulk density measurement)
About 250 g of the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2 subjected to saturated moisture absorption were weighed and filled into a glass graduated cylinder having an inner diameter of 36.2 mm. After tapping 5000 times with a tapping machine, the volume of the heat storage material was read, and the bulk density was calculated by the following equation.
Formula: Bulk density (g / L) = weight of heat storage material (g) / volume of heat storage material (L)
Moreover, the theoretical value of the bulk density of the heat storage material of Examples 1-9 was computed from following Formula.
Formula: Theoretical value of bulk density (g / L) = (bulk density of heat storage material of comparative example 1) × (content ratio (mass ratio) of 4A 8 × 12) + (bulk density of heat storage material of comparative example 2) × (4A 16 × 30 content ratio (mass ratio)
Note that “4A 8 × 12” (second heat storage material) and “4A 16 × 30” (first heat storage material) are the A-type zeolites used for producing the heat storage materials of Examples 1 to 9. “4A 8 × 12” is the heat storage material of Comparative Example 2, and “4A 16 × 30” is also the heat storage material of Comparative Example 1. Details of “4A 8 × 12” and “4A 16 × 30” will be described in “Production of Thermal Storage Materials of Examples and Comparative Examples” described later.

(Abrasion reduction)
The heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2 that were saturated and absorbed were weighed (W1 (g)). Next, the sample was filled in the glass bottle, ion-exchanged water was poured to the neck of the glass bottle, and the lid was tightly closed so that the liquid did not leak. The glass bottle was set on a shaker and shaken. The number of rotations of shaking was 700 ± 30 rpm, and the vibration time was 30 minutes.
After shaking, the glass bottle was removed, the sample was filtered and washed, and the filtrate containing wear powder generated from the heat storage material was collected in a pre-weighed beaker (W2 (g)). The filtrate was then evaporated to dryness with a 200 ° C. dryer until the weight was constant. The beaker was cooled to room temperature in a desiccator and then weighed again (W3 (g)).
The amount of wear reduction was calculated by the following formula.
Formula: Amount of wear reduction (w%) = {(W3-W2) / W1} × 100
Moreover, the theoretical value of the wear reduction amount of the heat storage material of Examples 1-9 was calculated by the following equation.
Formula: Theoretical value of wear reduction (w%) = (wear reduction rate of heat storage material of Comparative Example 1) × (content ratio of 4A 8 × 12) + (wear reduction rate of heat storage material of Comparative Example 2) × ( 4A 16 × 30 content ratio)
In addition, since the heat storage material is not worn as the wear reduction amount of the heat storage material is small, the wear resistance of the heat storage material is high as the wear reduction amount of the heat storage material is small.

(Moisture adsorption capacity per unit volume (L))
The weight of the empty crucible was measured (W4 (g)). About 10 g of the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2 which were saturated and absorbed were filled in the crucible, and the weight of the crucible was measured again (W5 (g)). The crucible containing the heat storage material was baked at a baking temperature of 450 ° C. for 1 hour, and after baking, the crucible containing the heat storage material was cooled to room temperature in a desiccator. And the weight of the crucible containing the heat storage material after cooling was measured (W6 (g)). And LOI (Loss on Ignition) 450 degreeC was computed from following Formula.
Formula: LOI 450 ° C. (wt%) = [1- (W6-W4) / (W5-W4)] × 100
And the actual value of the moisture adsorption capacity per unit volume was computed from the following formula.
Formula: Moisture adsorption capacity per unit volume (g / L) = LOI 450 ° C. × bulk density (actual value) / 100 × 1000
Furthermore, the theoretical value of the water | moisture-content adsorption capacity per unit volume of the thermal storage material of Examples 1-9 was computed from following Formula.
Formula: Theoretical value of moisture adsorption capacity per unit volume (g / L) = LOI 450 ° C. × bulk density (theoretical value) / 100

(Compressive strength)
About 2 g of the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2 which were saturated and absorbed were precisely weighed and filled in a powder molding die having a diameter of 15 mm and a depth of 45 mm. Next, a punch was inserted from the upper part of the mold and installed in a Kiya-type strength meter. A load was applied to the punch at a speed of 0.056 mm / sec, and the load at which cracking occurred in the heat storage material was recorded.

(Heat storage performance)
20 g of each of the heat storage materials of Examples 2, 4, 5, 6, 7 and Comparative Examples 1 and 2 calcined at 450 ° C. for 1 hour were weighed, and each was made of Pyrex (registered trademark) containing 25 ml of ion-exchanged water. It was put into a 100 ml graduated cylinder at once. The water temperature before charging and the maximum temperature after charging were measured with a digital thermometer, and the heat storage performance was calculated as the heating temperature (° C.) from the temperature difference. Each measurement used the same apparatus.

(Ion exchange rate of ion-exchangeable cation divalent metal)
Ion exchange was performed according to the method described in the specification text, and the ion exchange rate of the divalent metal ion exchange zeolite was determined using the following measuring apparatus and measurement conditions.
・ Measurement conditions: Quantitative analysis with fluorescent X-ray measuring device (“XRF-1700” manufactured by Shimadzu Corporation) ・ Ion exchange rate calculation: The number of divalent metals per aluminum atom is quantified using a calibration curve. The ion exchange rate of the divalent metal was calculated.

[Production of heat storage materials of Examples and Comparative Examples]
The heat storage material of Examples 1-9 and the heat storage material of Comparative Examples 1 and 2 were produced as follows.
Union Showa Co., Ltd. 4A type synthetic zeolite granular desiccant “4A 8 × 12” and Union Showa Co., Ltd. 4A type synthetic zeolite granular desiccant “4A 16 × 30” at a temperature of 25 ° C. and a humidity of 98% What was hold | maintained to the hold | maintenance moisture absorption shelf for 48 hours, and saturated moisture absorption was used for preparation of the heat storage material of Examples 1-9 and the heat storage material of Comparative Examples 1 and 2. The particle size of “4A 8 × 12” is 8 to 12 mesh of ASTM standard, and the particle size of “4A 16 × 30” is 16 to 30 mesh of ASTM standard.

  Regarding the heat storage materials of “4A 8 × 12” and “4A 16 × 30”, respectively, 6.5 mesh, 7.5 mesh, 8.6 mesh, 10 mesh, 12 mesh, 14 mesh, 16 mesh, 18 mesh, Using a 22-mesh, 26-mesh, 30-mesh, and 36-mesh JIS standard sieves, shake with a low-tap sieve shaker for 5 minutes, and then measure the weight of the heat storage material remaining on each sieve. By dividing the fraction weight by the total weight of the screened heat storage material, calculating the fraction fraction of each sieve, the particle size distribution of the heat storage materials of “4A 8 × 12” and “4A 16 × 30” It was measured. And the opening of the sieve with the highest fraction was defined as the peak position of the particle size distribution peak. The results are shown in Table 1. Thus, the peak position of the particle size distribution peak of “4A 8 × 12” is 2 mm (2000 μm), and the peak position of the particle size distribution peak of “4A 16 × 30” is 0.71 mm (710 μm). .

  Subsequently, the heat storage materials of Examples 1 to 9 and the heat storage materials of Comparative Examples 1 and 2 were produced by mixing “4A 8 × 12” and “4A 16 × 30” at the ratio shown in Table 2 below. .

  Furthermore, regarding the heat storage material of Example 6, ion exchange was performed by the following method about magnesium, cobalt, and calcium.

Example 10
After 50 g of the heat storage material of Example 6 was absorbed in the air overnight, it was placed in a 300 mL Erlenmeyer flask, 100 mL of an aqueous solution having a magnesium chloride concentration of 2.0 mol / L was added, and then about 7 at 60 ° C. in an oil bath. Soaked for more than an hour. In addition, the Erlenmeyer flask was shaken every 1 to 2 hours so that the zeolite was sufficiently mixed. Subsequently, the heat storage material was filtered and washed with hot water under reduced pressure until the pH of the filtrate became neutral by the pH test paper. For washing, 1 L of distilled water was used in total, and washing was sufficiently performed even after neutralization with pH test paper. The zeolite remaining on the filter paper was dried at 120 ° C. for 2 hours to obtain a heat storage material of Example 10 in which the heat storage material of Example 6 was replaced with magnesium ions. The magnesium ion exchange rate of the ion-exchangeable cation was 49%.

Example 11
Except for using cobalt chloride instead of magnesium chloride, ion exchange was performed in the same manner as in Example 10 to obtain a heat storage material of Example 11 in which the heat storage material of Example 6 was replaced with cobalt ions. The cobalt ion exchange rate of the ion-exchangeable cation was 65%.

Example 12
Except for using calcium chloride instead of magnesium chloride, ion exchange was performed in the same manner as in Example 10 to obtain a heat storage material of Example 12 in which the heat storage material of Example 6 was replaced with calcium ions. The calcium ion exchange rate of the ion-exchangeable cation was 89%.

[Evaluation results]
Table 3 below shows the evaluation results of bulk density, wear reduction, adsorption capacity per unit volume (L), and compressive strength of the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2. In addition, in the heat storage materials of Examples 1 to 9 and Comparative Examples 1 and 2, a graph with the content rate of 4A 16 × 30 on the horizontal axis and the bulk density on the vertical axis is shown in FIG. 1 and the content rate of 4A 16 × 30. 2 is a graph with the horizontal axis representing the amount of wear reduction and the vertical axis representing the amount of wear reduction. Further, FIG. 3 is a graph in which the horizontal axis represents the content of 4A 16 × 30 and the vertical axis represents the moisture adsorption capacity per unit volume (L).
Furthermore, the evaluation results of the heat storage performance of Examples 2, 4, 5, 6, 7 and Comparative Examples 1 and 2 are shown in Table 4, and the graph shows the content of 4A 16 × 30 on the horizontal axis and the exothermic temperature on the vertical axis. Are shown in FIG.

As shown in Table 3, by comparing Examples 1 to 9 and Comparative Examples 1 and 2, a heat storage material having a particle size distribution peak at a plurality of different peak positions is a heat storage material having one particle size distribution peak. It was found that the bulk density can be increased as compared with. From this, it was found that by using a heat storage material having particle size distribution peaks at a plurality of different peak positions, the packing density of the heat storage material can be increased. Thereby, a thermal storage apparatus can be reduced in size.
In addition, by comparing Examples 1 to 9 and Comparative Examples 1 and 2, the heat storage material having a particle size distribution peak at a plurality of different peak positions is unit volume compared to the heat storage material having one particle size distribution peak. It was found that the adsorption capacity per hit can be increased. As a result, by using a heat storage material having particle size distribution peaks at a plurality of different peak positions, a smaller amount of heat storage material is equivalent when the adsorbate is water or water vapor compared to a heat storage material having one particle size distribution peak. It was found that an amount of moisture could be adsorbed and correspondingly the same heat storage performance could be achieved. Thereby, a thermal storage apparatus can be reduced in size.

  Since the wear resistance of the heat storage material of Comparative Example 2 is lower than the wear resistance of the heat storage material of Comparative Example 1, Examples 1 to 1 prepared by mixing the heat storage material of Comparative Example 1 and the heat storage material of Comparative Example 2 were prepared. The wear resistance of the heat storage material of No. 8 was lower than the wear resistance of the heat storage material of Comparative Example 1. However, when comparing the theoretical value and the actual measurement value in the wear resistance of the heat storage material of Examples 1 to 8, the wear resistance of the heat storage material of Examples 1 to 8 is compared to the mixing of the heat storage material having low wear resistance. It was found that the nature is high. From this, it was found that the wear resistance of the heat storage material can be enhanced by using the heat storage material having particle size distribution peaks at a plurality of different peak positions. As a result, even if the heat storage device receives vibration from the outside, the heat storage material contained in the heat storage device wears out, and dust generated thereby deteriorates air permeability and liquid permeability, or the sliding surface of the compressor It is possible to suppress damage or blocking of the pores of the expansion valve.

  Since the compressive strength of the heat storage material of Comparative Example 1 is lower than the compression strength of the heat storage material of Comparative Example 2, the heat storage material produced by mixing the heat storage material of Comparative Example 1 and the heat storage material of Comparative Example 2 is a comparative example. The compressive strength of the heat storage material of Examples 1 and 2 having a high content ratio of 1 was lower than the compression strength of the heat storage material of Comparative Example 2. Further, among the heat storage materials produced by mixing the heat storage material of Comparative Example 1 and the heat storage material of Comparative Example 2, the content ratio of the heat storage material of Comparative Example 2 is high. It was lower than the compressive strength of the heat storage material of Comparative Example 2. This is because the content ratio of the heat storage material of Comparative Example 1 was extremely low, and it was easy to be isolated. Therefore, when compressing, the load could not be distributed to a plurality of heat storage materials, and therefore locally of Comparative Example 1 This is because the heat storage material has been crushed. However, it turned out that the compressive strength of the heat storage material of Examples 3-7 is higher than the compressive strength of the heat storage material of Comparative Examples 1 and 2. From this, it was found that the compressive strength of the heat storage material can be increased by using the heat storage material having particle size distribution peaks at a plurality of different peak positions. As a result, even if the heat storage device receives pressure from the outside, the heat storage material contained in the heat storage device is crushed, and the dust generated thereby deteriorates air permeability and liquid permeability, or the sliding surface of the compressor It is possible to suppress damage or blocking of the pores of the expansion valve.

By comparing the exothermic temperatures in the heat storage materials of Examples 2, 4, 5, 6, 7 and Comparative Examples 1 and 2, which were previously baked and dehydrated at 450 ° C., they have particle size distribution peaks at a plurality of different peak positions. The bulk density is increased by mixing the first heat storage material (4A 16 × 30) and the second heat storage material (4A 8 × 12) as compared to the heat storage material having one particle size distribution peak among the heat storage materials. Of those that could be done, it was found that those having a large ratio of the second heat storage material can raise the heat generation temperature. Accordingly, the first heat storage material (4A) having the first particle size distribution peak from the viewpoint of filling the heat storage material with higher density and improving the amount of heat generated compared to the heat storage material having one particle size distribution. 16 × 30) and the second heat storage material (4A 8 × 12) having a second particle size distribution peak (first heat storage material: second heat storage material) is preferably 5:95 to 95 : 5, more preferably 10:90 to 90:10, still more preferably 20:80 to 80:20, still more preferably 30:70 to 70:30, still more preferably 30:70. It was found to be ~ 50: 50.
That is, Examples 2, 4, 5, 6, 7 and Comparative Examples 1 and 2 in which the content ratio between the heat storage material of synthetic zeolite 4A 16 × 30 (Comparative Example 1) and 4A 8 × 12 (Comparative Example 2) was changed. From Table 4 which shows the result of measuring the heat storage performance of the sample by the above-mentioned method, the heat generation was performed in Example 6, ie, 4A 8 × 12 content ratio 60 wt%, by comparing the heat generation temperature per 20 g of each Example and Comparative Example. It was confirmed that the temperature was the highest at 58.4 ° C. In addition, it was found that even in Examples 5 and 7, a higher heat generation temperature than in Comparative Example 2 was obtained.

[Heat storage performance evaluation of Examples 10 to 12 using ion exchange heat storage material of Example 6]
In contrast to Example 6 in which the cation having high heat storage performance is Na, the ion-exchangeable cation is a divalent metal ion such as magnesium ion (Example 10), cobalt ion (Example 11), calcium ion. Using each synthetic zeolite, which was changed according to the above-described ion exchange method so as to be (Example 12), the exothermic temperature was measured in the same manner as in the heat storage evaluation described above. The results are shown in Table 5.

  The heat storage performance was most excellent in synthetic zeolite in which 49% of the number of exchangeable ions was replaced by magnesium ions in the A-type synthetic zeolite. From these results, it was confirmed that heat storage performance is improved by performing divalent metal ion exchange.

  Since the heat storage material of the present invention is excellent in heat storage performance, it is a heat storage device that requires high heat conversion efficiency such as an adsorption heat pump, or a heat storage device that further reduces the storage capacity of the heat storage material and requires downsizing. It can be suitably used.

Claims (6)

  A heat storage material composed of granular synthetic zeolite, which is one or a mixture of two or more selected from A-type synthetic zeolite, X-type synthetic zeolite, and Y-type synthetic zeolite, A heat storage material having at least a particle size distribution peak and a second particle size distribution peak. The peak position of the first particle size distribution peak of the synthetic zeolite is 0.25 mm or more and less than 1.5 mm, and the peak position of the second particle size distribution peak is 1.5 mm or more and 5 mm or less. Heat storage material.   The heat storage material according to claim 1 or 2, wherein 10% or more of the number of cations capable of ion exchange in the synthetic zeolite is a divalent metal ion.   4. The heat storage material according to claim 1, wherein 40% or more of the number of cations capable of ion exchange in the synthetic zeolite is at least one selected from magnesium ions, cobalt ions, and calcium ions. The heat storage material according to any one of claims 1 to 4, wherein a bulk density in a saturated moisture adsorption state is 1040 g / L or more.   The heat storage material according to any one of claims 1 to 5, wherein a moisture adsorption amount per unit volume is 193 g / L or more.