JP2012025791A - Heat storage material and heat accumulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel heat storage material which has no risk of inflammability, has enough heat storage performance as a heat storage material, and can generate hydrate at a temperature that is appropriate for cooling air conditioning, and to provide a heat accumulator.SOLUTION: The heat storage material is obtained by mixing a guest substance and water that is a host substance, and cooling the mixture to generate the hydrate, wherein tetrabutylammonium acrylate is used as the guest substance.

Description

  The present invention relates to a heat storage material and a heat storage device that mix a guest material and water as a host material and cool the mixture to generate a class hydrate.

  Clathrate hydrate (clathrate hydrate, hereinafter simply referred to as hydrate) is an icy solid substance formed from a hydrophobic molecule such as methane and a water molecule, and the water molecule (host substance) When in contact with a clathrate hydrate-generating molecule (guest material) under low temperature and high pressure conditions, a crystal structure is formed that includes the guest material.

  Hydrates generate heat when generated and absorb heat when decomposed, and can be used as a heat storage material. For example, hydrates are generated at midnight power and used as a cooling source for daytime cooling. Things are being done.

  The present inventors have proposed in Patent Document 1 that cyclopentane is used as a guest substance and a dispersion obtained by emulsifying this and water with a surfactant is used as a heat storage material.

JP 2008-285526 A JP 2007-246778 A

  However, a heat storage material using cyclopentane as a guest material may ignite and may not ensure safety. Therefore, development of a heat storage material that is free from the risk of ignition is desired.

  For example, Patent Document 2 discloses a heat storage material that uses tetra-n-butylammonium bromide (TBAB) as a guest material as a heat storage material that has no risk of ignition.

  Therefore, the present inventors have no possibility of ignition, have excellent heat storage performance equivalent to TBAB (hydrate formation / decomposition heat amount), and are suitable for cooling air conditioning temperature at 0 to 20 ° C. A new heat storage material guest material that can be produced was investigated.

  The present invention has been made in view of the above circumstances, and there is no possibility of ignition, a novel heat storage material and a heat storage device that have sufficient heat storage performance as a heat storage material and can generate hydrates at a temperature suitable for cooling air conditioning. The purpose is to provide.

  In order to achieve the above object, the invention according to claim 1 is a heat storage material in which a guest substance and water as a host substance are mixed and cooled to produce a hydrate. As the guest substance, tetrabutylammonium acrylate is used. Is a heat storage material.

  The invention according to claim 2 is the heat storage material according to claim 1, wherein the tetrabutylammonium acrylate is 30 parts by mass or more and 40 parts by mass or less, out of a total of 100 parts by mass of the guest substance and the host substance.

  Invention of Claim 3 is the heat storage tank with which the heat storage material of Claim 1 or 2 was filled, the cooling means which cools the said heat storage material, and produces | generates a hydrate, The said heat storage which became hydrate And a heat utilization means for decomposing the material and taking out the cold energy of the heat storage material.

  The invention according to claim 4 is a capsule filled with the heat storage material according to claim 1, a heat storage tank into which the capsule is charged and filled with a refrigerant, and cooling the refrigerant in the capsule. Cooling means for cooling the heat storage material to generate a hydrate, and heat utilization means for decomposing the heat storage material that has become a hydrate and taking out the cold heat of the heat storage material through the refrigerant. It is a heat storage device.

  The invention according to claim 5 is a heat transfer tube assembly filled with the heat storage material according to claim 1, a heat storage tank in which the heat transfer tube assembly is arranged and filled with a refrigerant, and cooling the refrigerant Cooling means for cooling the heat storage material in the heat transfer tube assembly to generate a hydrate, and decomposing the heat storage material that has become a hydrate to take out the cold heat of the heat storage material through the refrigerant A heat storage device.

  ADVANTAGE OF THE INVENTION According to this invention, there is no fear of ignition, it has sufficient heat storage performance as a heat storage material, and the novel heat storage material and heat storage apparatus which can produce | generate a hydrate at the temperature suitable for cooling air conditioning can be provided.

It is a figure which shows the result of the differential scanning calorimetry (DSC) of the thermal storage material of this invention. It is the figure which put together the data obtained by differential scanning calorimetry (DSC) about this invention and the conventional heat storage material. It is the schematic of the thermal storage apparatus which concerns on one embodiment of this invention. It is the schematic of the thermal storage apparatus which concerns on one embodiment of this invention. It is the schematic of the thermal storage apparatus which concerns on one embodiment of this invention.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  As described above, the guest material of the heat storage material that generates hydrates by cooling has no risk of ignition, has sufficient heat storage performance as a heat storage material, and water at 0 to 20 ° C. suitable for cooling air conditioning temperature It is required to produce a Japanese product.

Results heat storage material for the present inventors have studied intensively to satisfy such requirements, the acrylic acid tetrabutylammonium _{((n-C 4 H 9} ) 4 N-CH 2 CHCOO; hereinafter referred TBAAc) is a hydrate It discovered that it produced | generated and came to this invention.

  The heat storage material according to the present embodiment is an aqueous solution obtained by mixing a guest substance and water as a host substance, and uses TBAAc as the guest substance.

  That is, the heat storage material according to the present embodiment is made of an aqueous solution of TBAAc. An aqueous solution of TBAAc can be obtained by adding water to TBAAc powder and stirring. Since the TBAAc powder is water-soluble, a heat storage material in which the guest substance is well dispersed can be obtained.

  A hydrate can be obtained by cooling the heat storage material at a temperature lower by about 3 ° C. than the hydrate formation temperature. In addition, this invention does not prescribe | regulate in particular about the shape and dimension of a hydrate crystal.

  TBAAc as a guest substance of the heat storage material is preferably 30 parts by mass or more and 40 parts by mass or less, out of a total of 100 parts by mass of the guest substance (TBAAc) and the host substance (water). This is because if TBAAc is less than 30 parts by mass, sufficient heat storage performance may not be ensured. On the other hand, if it is more than 40 parts by mass, surplus guest substances will precipitate when hydrates are generated. This is because it interferes with repeated operation and the cost of the heat storage material increases.

  Next, the thermal storage temperature (hydrate formation / decomposition temperature) of the thermal storage material of the present invention using TBAAc as a guest substance and the amount of heat at that time were determined by differential scanning calorimetry (DSC), and the results are shown in FIG. Indicated. In FIG. 1, the vertical axis represents heat flow (mW) and the horizontal axis represents temperature (° C.). Further, in the curve (DSC curve) 10 obtained by this measurement, the peak appearing below the baseline B represents an endothermic reaction.

  This measurement was performed using a 30 mass% TBAAc aqueous solution in a nitrogen atmosphere (nitrogen gas flow rate of 20 ml / min). The TBAAc used for the measurement is 14.41 mg. In addition, the temperature program for the measurement was as follows: from room temperature to −40 ° C. at a rate of 10 ° C./min, then from −40 ° C. to −5 ° C. at a rate of 5 ° C./min, The temperature was set to increase in min. FIG. 1 shows an endothermic peak that appears when the temperature is raised from −5 ° C. to 35 ° C.

  From FIG. 1, the 30 mass% TBAAc aqueous solution had a heat storage temperature of 17.60 ° C. and a heat quantity of 179.04 J / g. Therefore, the heat storage material made of 30 mass% TBAAc aqueous solution generates / decomposes hydrate at 17.60 ° C., and the heat storage amount (generation / decomposition heat amount of hydrate) is 179.04 kJ / kg.

  The heat storage temperature and the amount of heat were determined in the same manner as conventionally used methods. That is, the amount of heat is obtained from the area formed by the endothermic peak P appearing below the baseline B of the DSC curve 10 and the extension line of the baseline B, and the heat storage temperature is the rise of the DSC curve 10 on the low temperature side of the endothermic peak P. It was determined from the intersection of the tangent of the part (that is, the tangent of the maximum gradient leading to the endothermic peak P) and the extension of the baseline.

  Subsequently, differential scanning calorimetry (DSC) was also performed on a tetra-n-butylammonium bromide (TBAB) aqueous solution, a dispersion obtained by dispersing cyclopentane (CP) in water, and ice (Ice) by the same method. These results are shown in Table 1.

  In Table 1, “heat storage density” indicates a heat storage amount (a hydrate formation / decomposition heat amount).

  From Table 1, the heat storage temperature of the 30 mass% TBAAc aqueous solution, which is the heat storage material of the present invention, is 17.6 ° C., which is about 8 ° C. higher than the heat storage temperature of the TBAB aqueous solution 9.9 ° C. Therefore, the temperature of the refrigerant at the time of cooling the heat storage material to produce a hydrate can be made higher than that of the heat storage material using the TBAB aqueous solution, and sufficient cooling for computer equipment cooling at a temperature of 15 to 20 ° C. On the other hand, the efficiency of the refrigerator can be increased.

  The heat storage density of this 30 mass% TBAAc aqueous solution is 179 kJ / kg. On the other hand, the 32 mass% TBAB aqueous solution has a heat storage density of 199 kJ / kg, and the heat storage density (heat storage amount) of the TBAA aqueous solution when the heat storage density (heat storage amount) of the TBAB aqueous solution is 1 is almost different from 0.90. There is no. That is, the heat storage material of the present invention has a heat storage performance equivalent to that of a heat storage material made of a TBAB aqueous solution.

  On the other hand, when the heat storage density (heat storage amount) of the CP dispersion liquid is 1, the heat storage density (heat storage amount) of the TBAAc aqueous solution is 0.63, and when the heat storage density (heat storage amount) of Ice is 1. The heat storage density (heat storage amount) of the TBAAc aqueous solution is 0.54, and the heat storage density (heat storage amount) of the TBAAc aqueous solution is smaller than the CP dispersion or Ice.

  Thus, although the TBAAc aqueous solution has a smaller heat storage density (heat storage amount) than the CP dispersion and Ice, there is no risk of ignition that is a concern with the CP dispersion. Moreover, since the heat storage temperature is about 18 degreeC higher than Ice, the temperature of the refrigerant | coolant at the time of cooling a heat storage material and producing | generating a hydrate can be raised, and the efficiency of a refrigerator can be improved.

  Next, a TBAAc aqueous solution having a hydration number of 35 was prepared by adjusting the concentration of the TBAAc aqueous solution to 33.2 mass%, and differential scanning calorimetry (DSC) was performed in the same manner as described above. Further, a TBAAc aqueous solution having a hydration number of 30 was prepared by adjusting the concentration of the TBAAc aqueous solution to 37 mass%, and a hydrate crystal decomposition observation test using a thermostatic bath was performed to measure the heat storage temperature. Table 2 and FIG. 2 summarize these results and the results of differential scanning calorimetry of the 30 mass% TBAAc aqueous solution (hydration number 40) described in Table 1. FIG. 2 also shows the results of differential scanning calorimetry of the TBAB aqueous solution (40 mass% and 32 mass%), CP dispersion, and Ice. In FIG. 2, the vertical axis represents the heat storage temperature (hydrate generation / decomposition temperature), and the horizontal axis represents the heat storage amount (hydrate generation / decomposition heat amount).

  As shown in Table 2 and FIG. 2, when the concentration of the TBAAc aqueous solution is 37 mass% to 30 mass%, the heat storage temperature is almost constant at about 18 ° C., and the heat storage density is 179.04 kJ / kg to 195.07 kJ. / Kg. This heat storage density is a value substantially equivalent to the heat storage density of the TBAB aqueous solution, and it can be seen that the 37 mass% to 30 mass% TBAAc aqueous solution has sufficient heat storage performance as a heat storage material. In addition, as a heat storage material of this invention, it is desirable to use 33.2 mass% TBAAc aqueous solution with high heat storage performance.

  As described above, in the heat storage material according to the present embodiment, TBAAc is used as a guest substance that generates a hydrate.

  Thereby, there is no fear of ignition, it has sufficient heat storage performance, and the heat storage material which produces | generates a hydrate at the temperature suitable for air conditioning can be implement | achieved.

  Furthermore, in the heat storage material using cyclopentane as the guest material, it is necessary to emulsify by adding a surfactant to improve the dispersibility because the layer is separated from water as the host material. Then, the TBAAc powder used as the guest material is water-soluble, and the guest material can be easily dispersed, so that it is not necessary to use a surfactant or the like.

  In addition, the heat storage temperature (hydrate formation / decomposition temperature) of the aqueous TBAAc solution is higher than the thermal storage temperature of the aqueous TBAB solution and about 18 ° C higher than the melting point of water. It is. For example, if it is used as a cooling device for a production machine or an air conditioner for computer equipment, the temperature of the refrigerant when it is cooled to produce a hydrate can be increased. Therefore, energy efficiency can be saved by increasing the efficiency of the refrigerator. It leads to.

  Next, a heat storage device using the heat storage material of the present invention will be described.

  As shown in FIG. 3, the heat storage device 30 according to the present embodiment includes a heat storage tank 31 filled with the heat storage material 1, a cooling unit 11 that cools the heat storage material 1 to generate a hydrate, and a hydrate The heat storage material 1 which decomposes | disassembles and becomes the heat | fever utilization means 12 which takes out the cold heat of the heat storage material 1 is provided.

  As the cooling means 11, a refrigerator 32, a cooling pipe 33 of the refrigerator 32, and a brine (or water) pump 34 for introducing a brine (or water) in the cooling pipe 33 into the refrigerator 32 are provided. In addition, a part of the cooling pipe 33 passes through the heat storage tank 31.

  Further, as the heat utilization means 12, a heat load 35 using heat storage, a heating tube (heat absorption tube) 36 of the heat load 35, and a brine (here, water is used) in the heating tube 36 are supplied to the heat load 35. The heat load water pump 37 is provided, and a part of the heating pipe 36 passes through the heat storage tank 31.

  In the heat storage device 30, the refrigerator 32 is driven using midnight power or the like, and brine (or water) is caused to flow through the cooling pipe 33 in the heat storage tank 31 by the brine (or water) pump 34 for the refrigerator. The inner heat storage material 1 is cooled to produce a hydrate. At this time, if the heat storage temperature is around 15 ° C., it is not necessary to use brine, and the system can be simplified by sharing the cooling pipe 33 and the heating pipe 36.

  Thereafter, when cooling, the heat load water pump 37 is driven to cause water to flow through the heating pipe 36 in the heat storage tank 31, where the hydrate is heated to cool the water, and the heat load 35 Cooling is performed by releasing cold heat.

  The heat storage tank 31 has a capacity for accommodating the heat storage material 1 having a capacity commensurate with the daytime cooling load of the heat load 35. In the present invention, since the TBAAc aqueous solution that does not ignite is used as the heat storage material 1, the heat storage device 30 can be operated more safely than the conventional technology using a cyclopentane dispersion.

  Another example of the heat storage device using the heat storage material of the present invention will be described.

  The heat storage device 40 shown in FIG. 4 includes a capsule 41 filled with the heat storage material 1, a heat storage tank 31 filled with the capsule 41 and charged with water 42 as a refrigerant, and a capsule by cooling the water 42. Cooling means 13 that cools the heat storage material 1 in 41 to generate a hydrate, and heat utilization means 14 that decomposes the heat storage material 1 that has become a hydrate and takes out the cold energy of the heat storage material 1 through the water 42. With.

  As the cooling means 13, a refrigerator 32 is connected to the heat storage tank 31 via a cooling circulation line 43, and a circulation pump 44 for introducing water 42 into the refrigerator 32 is provided in the cooling circulation line 43. Further, as the heat utilization means 14, a heat load 35 is connected to the heat storage tank 31 via a heating circulation line 45, and a circulation pump 46 that supplies water 42 to the heat load 35 is provided in the heating circulation line 45. .

  In the heat storage device 40, the water 42 introduced into the refrigerator 32 by the circulation pump 44 is cooled by midnight power or the like, the water 42 is returned to the heat storage tank 31, and the heat storage material 1 in the capsule 41 is cooled and hydrated. Produce things. Further, at the time of use such as cooling, the water 42 is supplied to the heat load 35 by the circulation pump 46, and the water 42 heated by the heat load 35 is returned to the heat storage tank 31. In the heat storage material 1 in the capsule 41, the hydrate is decomposed by cooling the heated water 42.

  The heat storage device 50 shown in FIG. 5 has basically the same configuration as the heat storage device 40 shown in FIG. 4, and instead of the capsule 41, a plurality of heat transfer tubes (heat transfer tube assembly) in which the heat storage material 31 is filled in the heat storage tank 31. Body) 51 is arranged.

  In the heat storage devices 40 and 50, since the heat storage tank 31 filled with water 42 is provided with the capsule 41 filled with the heat storage material 1 or the heat transfer tube assembly 51 filled with the heat storage material 1, the existing heat storage device (ice heat storage device) is provided. Etc.) and the introduction cost can be kept low.

  In the heat storage devices 40 and 50, the water 42 in the heat storage tank 31 is directly introduced into the refrigerator 32 and the heat load 35, but a cooling heat exchanger and a heating heat exchanger may be provided as necessary.

Claims (5)

In the heat storage material that mixes the guest material and water, which is the host material, and cools it to produce hydrates,
A heat storage material using tetrabutylammonium acrylate as the guest material.   2. The heat storage material according to claim 1, wherein the tetrabutylammonium acrylate is 30 parts by mass or more and 40 parts by mass or less, out of a total of 100 parts by mass of the guest substance and the host substance. A heat storage tank filled with the heat storage material according to claim 1 or 2,
Cooling means for cooling the heat storage material to produce a hydrate;
Heat utilization means for decomposing the heat storage material that has become a hydrate and extracting the cold energy of the heat storage material;
A heat storage device characterized by comprising: A capsule filled with the heat storage material according to claim 1 or 2, a heat storage tank filled with a refrigerant while the capsule is charged,
Cooling means for cooling the heat storage material in the capsule by cooling the refrigerant to generate a hydrate;
Heat utilization means for decomposing the heat storage material that has become a hydrate and taking out the cold energy of the heat storage material through the refrigerant;
A heat storage device characterized by comprising: A heat transfer tube assembly filled with the heat storage material according to claim 1, and a heat storage tank in which the heat transfer tube assembly is arranged and filled with a refrigerant,
A cooling means for cooling the heat storage material in the heat transfer tube assembly by cooling the refrigerant to generate a hydrate;
Heat utilization means for decomposing the heat storage material that has become a hydrate and taking out the cold energy of the heat storage material through the refrigerant;
A heat storage device characterized by comprising:

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