JP2017040380A - Chemical heat storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of heat generation performance in a chemical heat storage device.SOLUTION: A chemical heat storage device 10 includes a storage 11 storing NH, and a heater 12 that has a particular reaction material 14 configured to generate heat due to a chemical reaction with NHand configured to desorb NHin a case of being heated. Between particles 19 of the reaction material 14, interposed are plural particle inclusions 17 having a smaller particle diameter than that of the particle 19 of the reactor material 14. The particle inclusion 17 is inactive to the reaction material 14 and NHat the time of regeneration reaction when NHis desorbed from the reaction material 14, and has a higher melting point than a temperature of the reaction material 14 at the time of regeneration reaction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chemical heat storage device.

As a conventional chemical heat storage device that heats a warm-up target, for example, a chemical heat storage device that is applied to an exhaust purification system that purifies exhaust discharged from an internal combustion engine of a vehicle is known (see, for example, Patent Document 1). . In the chemical heat storage device applied to the exhaust gas purification system, when the temperature of the exhaust gas discharged from the internal combustion engine becomes lower than the warm-up start temperature, NH ₃ which is a reaction medium stored in the reservoir reacts through the supply pipe. Supplied to the vessel. As a result, the supplied NH ₃ and the reaction material in the reactor chemically react to generate heat. That is, an exothermic reaction occurs. Exhaust as a heating target is heated via a heat exchanger or the like by heat generated by the exothermic reaction. Further, when the temperature of the exhaust discharged from the internal combustion engine becomes higher than the reaction medium regeneration temperature, the heat of the exhaust is given to the reaction material in the reactor, and NH ₃ is desorbed from the reaction material in the reactor. That is, a regeneration reaction occurs. Then, the desorbed NH ₃ is collected in the reservoir through the supply pipe.

JP 2013-72558 A

When the reaction material and NH ₃ react and NH ₃ is taken into the crystal of the reaction material, the melting point of the reaction material falls below the original melting point of the reaction material. For this reason, in the conventional chemical heat storage device, when the reaction material in the reactor is exposed to a high temperature state for a long time during the regeneration reaction after the exothermic reaction is completed, a part of the particles of the reaction material is melted, There is a possibility that the number of pores constituting the NH ₃ diffusion channel existing on the surface of the reaction material particles may be reduced. Here, the term “melting” includes not only a flow phenomenon that occurs when the melting point is reached but also a particle enlargement phenomenon (sintering) at a temperature lower than the melting point. When the pores present on the surface of the reaction material particles are reduced, the diffusion rate of NH ₃ supplied to the reactor into the reaction material becomes slow. That is, the reaction rate between the reaction material and NH ₃ decreases. As a result, there is a problem that heat generation performance in the chemical heat storage device is lowered.

  An object of this invention is to provide the chemical thermal storage apparatus which can suppress the fall of exothermic performance.

Chemical heat storage device according to the present invention includes a reservoir for storing NH _3, when heated together generates heat by chemical reaction between NH ₃ and reactor with a particulate reactive material capable of leaving the NH _3, the A plurality of particle inclusions having a particle diameter smaller than that of the reaction material particles are interposed between the particles of the reaction material, and the particle inclusions are used during the regeneration reaction in which NH ₃ is desorbed from the reaction material. In addition to being inert to the reaction material and NH ₃ , it has a melting point higher than the temperature of the reaction material during the regeneration reaction.

In the chemical heat storage device according to the present invention, a plurality of particle inclusions having a particle size smaller than the particles of the reaction material are interposed between the particles of the reaction material. The plurality of particle inclusions are inactive to the reaction material and NH ₃ during the regeneration reaction in which NH ₃ is desorbed from the reaction material, and thus do not chemically react with the reaction material and NH ₃ . Furthermore, since the plurality of particle inclusions have a melting point higher than the temperature of the reaction material during the regeneration reaction, it is difficult to melt even if the reaction material becomes high temperature during the regeneration reaction. Therefore, even when the reaction material is melted during the regeneration reaction, a plurality of particle inclusions are present between the particles of the reaction material due to the presence of a plurality of such particle inclusions that are inert and have a high melting point. A diffusion flow path of NH ₃ can be secured by a gap between them. Then, when the exothermic reaction after the regeneration reaction can be reliably supplied to NH ₃ by diffusion channel of NH ₃ which is secured by a plurality of particle inclusions, it is possible to suppress the reduction of the reaction rate. As a result, it is possible to suppress a decrease in heat generation performance in the chemical heat storage device.

  In the chemical heat storage device according to the present invention, the ratio of the total volume of the plurality of particle inclusions to the total of the total volume of the reaction material and the total volume of the plurality of particle inclusions may be 60 volume percent or less. In this case, an increase in the heat capacity of the plurality of particle inclusions can be suppressed. Thereby, the effect which suppresses the fall of the heat generation performance in a chemical heat storage apparatus with a plurality of particle inclusions can be surely exhibited.

In the chemical heat storage device according to the present invention, the particle diameter of the particle inclusion may be 3 nm or more. In this case, a gap through which NH ₃ molecules can pass can be easily formed between the plurality of particle inclusions, and a diffusion flow path of NH ₃ can be reliably ensured.

In the chemical heat storage device according to the present invention, the particle inclusion may be SiC, SiO ₂ , or Ni fine particles. In this case, SiC, SiO ₂ , or Ni is inert to, for example, a reaction material in which a halide is used and NH ₃ and has a higher melting point than, for example, a reaction material in which a halide is used. It is suitable as an inclusion, and a diffusion channel for NH ₃ can be reliably ensured.

  ADVANTAGE OF THE INVENTION According to this invention, the chemical thermal storage apparatus which can suppress the fall of heat_generation | fever performance is provided.

It is a schematic block diagram which shows the exhaust gas purification system provided with the chemical heat storage apparatus which concerns on one Embodiment of this invention. It is a conceptual diagram which shows a mode that the some particle | grain inclusion is disperse | distributing between the particle | grains of a reaction material. It is a conceptual diagram which shows a mode that the particle | grains of a reaction material fuse | melt at the time of regeneration reaction in the conventional chemical heat storage apparatus. Is a graph showing the temperature change during the exothermic reaction of MgBr ₂ in the case where the particles inclusions is not added. It is a graph which shows the change of exothermic temperature according to the addition rate of inclusions.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  With reference to FIG. 1, the exhaust gas purification system provided with the chemical heat storage apparatus which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram illustrating an exhaust purification system including a chemical heat storage device according to an embodiment of the present invention.

  The exhaust purification system 1 is disposed in an exhaust system of a diesel engine 2 (hereinafter simply referred to as an engine 2) that is an internal combustion engine of a vehicle, and removes harmful substances (environmental pollutants) contained in exhaust discharged from the engine 2. Purify. The exhaust purification system 1 includes a heat exchanger 4, an oxidation catalyst (DOC: Diesel Oxidation Catalyst) 5, which are arranged in order from an upstream side to a downstream side in an exhaust pipe 3 that is an exhaust passage connected to an engine 2. A diesel exhaust particulate filter (DPF) 6, a selective catalytic reduction (SCR) 7, and an oxidation catalyst (ASC: Ammonia Slip Catalyst) 8 are provided.

The heat exchanger 4 transfers heat between the exhaust from the engine 2 and a reaction material 14 described later. The heat exchanger 4 has a honeycomb structure, for example. The DOC 5 oxidizes and purifies HC and CO contained in the exhaust. The DPF 6 collects and removes particulate matter (PM) contained in the exhaust gas. The SCR 7 reduces and purifies NOx contained in the exhaust with urea or ammonia (NH ₃ ). The ASC 8 oxidizes and purifies NH ₃ that has passed through the SCR 7 and has flowed downstream of the SCR 7.

  Each catalyst of DOC5, SCR7, and ASC8 has a temperature range that can exhibit the ability to purify environmental pollutants, that is, an activation temperature. However, immediately after the engine 2 is started, the temperature of the exhaust gas immediately after being discharged from the engine 2 is as low as about 100 ° C., and may be lower than the activation temperature of each catalyst. Even in such a case, it is necessary to quickly bring the temperature of each catalyst to the activation temperature in order to exhibit the purification ability of each catalyst.

  Therefore, the exhaust gas purification system 1 according to the present embodiment includes a chemical heat storage device 10 that heats the exhaust gas via the heat exchanger 4 arranged on the most upstream side of the exhaust pipe 3. When the chemical heat storage device 10 heats the exhaust gas via the heat exchanger 4, the exhaust gas whose temperature is higher than that of the upstream side flows on the downstream side of the heat exchanger 4, and the catalyst is activated early. Can do.

The chemical heat storage device 10 uses the NH ₃ as a reaction medium and utilizes a reversible chemical reaction to heat the exhaust gas to be heated via the heat exchanger 4 without any external energy. In other words, the chemical heat storage device 10 is typically leave accumulated heat by the state to separate the reaction member 14 and the NH ₃ to be described later, when the heating of the heat exchanger 4 is required, reacting the NH ₃ By supplying to the material 14, heat is generated from the reaction material 14 and the exhaust gas is heated through the heat exchanger 4.

  The chemical heat storage device 10 includes a storage 11 (reservoir), a heater 12 (reactor), a supply pipe 15, and a valve 16.

Storage 11 includes an adsorbent 13 capable of leaving the holding and NH ₃ by physical adsorption of NH _3. As the adsorbent 13, activated carbon, carbon black, mesoporous carbon, nanocarbon, zeolite, or the like is used. Storage 11, by physically adsorbed NH ₃ to the adsorbent 13, for storing NH _3.

  The heater 12 is disposed around the exhaust pipe 3 so as to correspond to the heat exchanger 4 in the exhaust pipe 3. That is, the heater 12 is disposed so as to heat the heat exchanger 4. The heater 12 has, for example, an annular cross section surrounding the exhaust pipe 3. The cross-section of the annular cross section is a surface obtained by cutting the heater 12 perpendicular to the exhaust flow direction in the exhaust pipe 3.

The heater 12 has a reactant mixture 18. The reactant mixture 18 includes particulate reactant 14. That is, the heater 12 has a reaction material 14. In the present embodiment, the particulate form includes a powder form constituted by fine particles such as powder. The reaction material 14 chemically reacts with NH ₃ to generate heat, and is heated by the heat of exhaust gas that has become high temperature to store heat and desorb NH ₃ . Therefore, in the heater 12, when NH ₃ is supplied from the storage 11, the NH ₃ and the reaction material 14 chemically react to generate heat. In the heater 12, when heat equal to or higher than the desorption start temperature is applied, NH ₃ is desorbed from the reaction material 14 and begins to release NH ₃ . Since the exothermic temperature and the desorption start temperature differ depending on the combination of NH _{3 as the} reaction medium and the reaction material 14, the reaction material 14 is appropriately selected according to the target heating temperature to be heated.

  As the reaction material 14, a halide represented by the composition formula MXa is used. Here, M is an alkaline earth metal such as Mg, Ca, or Sr, or a transition metal such as Cr, Mn, Fe, Co, Ni, Cu, or Zn. X is Cl, Br, I or the like. a is a number specified by the valence of M, and is 2-3.

Further, in the present embodiment, the reactant mixture 18 includes a plurality of particle inclusions 17 having a particle diameter smaller than the particles of the reactant 14. That is, in the reaction material mixture 18, the particulate reaction material 14 and the plurality of particle inclusions 17 are mixed. The reaction material mixture 18 is press-molded in a state where a plurality of particle inclusions 17 are added to the particulate reaction material 14. By this press molding, the reaction material mixture 18 is molded into a molded body such as a plate shape, a pellet shape, or a tablet shape. For example, the reaction material mixture 18 is obtained by uniformly mixing the particulate reaction material 14 and the plurality of particle inclusions 17 with a powder mixer or the like, and placing the mixture in a mold, for example, at a pressure of 20 to 100 MPa. It is formed by pressing and compacting. By forming the reaction material mixture 18 in this way, a plurality of particle inclusions 17 having a smaller particle diameter than the particles of the reaction material 14 are interposed between the particles of the reaction material 14. FIG. 2 is a conceptual diagram showing a state in which a plurality of particle inclusions 17 are dispersed between the particles 19 of the reaction material 14. As shown in FIG. 2, the plurality of particle inclusions 17 are interposed between the particles 19 of the reaction material 14, and NH ₃ diffusion channels are formed between the plurality of particle inclusions 17.

  The particle inclusion 17 is a particulate microstructure, and has a smaller particle diameter than the particles 19 of the reaction material 14. Thereby, the particle inclusions 17 can be interposed between the particles 19 of the reaction material 14. Here, the particle diameter is a value corresponding to the diameter when the particle is assumed to be a substantially spherical body, for example. The particle diameter is not limited to the diameter, and may be defined according to the size and shape of the particle 19 or the particle inclusion 17. For example, the particle diameter may be a major axis or a minor axis, or may be a particle length measured according to another predetermined standard. Further, the particle diameter may be, for example, an average particle diameter that is an average value of the particle diameters of a plurality of particles, or may be a particle diameter of any particle selected from the plurality of particles. More specifically, the particle diameter may be an equivalent particle diameter calculated from geometric characteristics, or an effective particle diameter calculated from dynamic characteristics or optical characteristics. For example, the effective diameter of the particle calculated from the optical characteristics is a particle diameter (D50) at which the cumulative volume in the particle size distribution measured by a laser diffraction / scattering particle diameter measuring apparatus is 50%.

The particle inclusion 17 is inactive to the reaction material 14 and NH ₃ during the regeneration reaction in which NH ₃ is desorbed from the reaction material 14, and has a melting point higher than the temperature of the reaction material 14 during the regeneration reaction. Have. Inactive means that it is chemically stable and difficult to react chemically. The regeneration reaction is a reaction in which heated heat of exhaust gas is applied to the reaction material 14 of the heater 12 and NH ₃ is desorbed from the reaction material 14, and the reaction from the right side to the left side in the reaction formula (A) described later is performed. It is a reaction. The temperature of the reaction material 14 at the time of the regeneration reaction is, for example, the peak temperature (for example, about 400) of the reaction material 14 that becomes the highest temperature during the regeneration reaction. Therefore, the particle inclusion 17 does not chemically react with the reactant 14 or NH ₃ during the regeneration reaction. In addition, the particle inclusions 17 themselves do not melt during the regeneration reaction. In the present embodiment, melting includes not only a flow phenomenon that occurs when the melting point is reached but also a particle enlargement phenomenon (sintering) at a temperature lower than the melting point. When the temperature of the reaction material 14 at the time of the regeneration reaction is, for example, about 400 ° C., the particle inclusions 17 can react to both the reaction material 14 and NH ₃ in a temperature environment of about 400 ° C., for example. It is made of a material that does not react chemically and does not melt itself.

The particle inclusion 17 is, for example, fine particles such as SiC, SiO ₂ , or Ni. The ratio of the total volume of the plurality of particle inclusions 17 to the total of the total volume of the reaction material 14 and the total volume of the plurality of particle inclusions 17 (hereinafter also referred to as “addition ratio of the particle inclusions 17”) is, for example, 60 It may be less than or equal to volume percent. That is, when the total of the total volume of the reaction material 14 and the total volume of the plurality of particle inclusions 17 is 100, the ratio of the total volume of the plurality of particle inclusions 17 to the total may be 60 or less. .

The upper limit value of the particle diameter of the particle inclusion 17 is appropriately set according to the type of the reaction material 14. For example, when the reaction material 14 is MgBr ₂ , the upper limit of the particle diameter of the particle inclusion 17 is, for example, about 3 to 800 nm, which is sufficiently smaller than about 1 to 50 μm that is the particle diameter of the MgBr ₂ particles. Also good. The particle size of the particle inclusions 17 may be such that a gap through which NH ₃ molecules can pass is formed between the particle inclusions 17. Therefore, the lower limit of the particle diameter of the particle inclusion 17 may be 3 nm, for example.

Here, 3 nm which is the lower limit value of the particle diameter of the particle inclusions 17 can be obtained by, for example, the following method. When the circles (outer circles) circumscribing each other and having the same diameter are arranged between the three circles (outer circles) and circumscribing these three circles (inner circles), the diameter of the inner circle is If X is X and the diameter of the outer circle is Y, the relationship X / Y≈0.155 is established, for example, based on the Cartesian circle theorem. Since the size of the NH ₃ molecule is about 4 mm, if the diameter of the inner circle is equal to the size of the molecule of NH ₃ (X = 4 mm), Y = 25.8Å≈3 nm is obtained. That is, the diameter Y of the outer circle when the NH ₃ molecule having a diameter of 4 mm can pass between the outer circles can be considered to be at least 3 nm. Since the diameter Y of the outer circle can be regarded as the particle diameter of the particle inclusions 17, the particle diameter of the particle inclusions 17 when the NH ₃ molecules can permeate through the gaps between the particle inclusions 17 is at least 3 nm. Can be considered. Therefore, if the particle diameter of the particle inclusions 17 is at least 3 nm, a gap through which NH ₃ molecules can pass can be easily formed between the inclusions.

  The reaction material 14 disposed in the heater 12 has a heat conductivity higher than that of the reaction material 14, and serves as a heat conduction path that efficiently transfers heat generated in the reaction material 14 to the heat exchanger 4. Materials may be mixed. For example, when forming the reaction material 14 into a plate-shaped, pellet-shaped, or tablet-shaped molded body, the powdered reaction material 14 and the heat conducting material are uniformly mixed with a powder mixer or the like, and the mixture is molded. It is also possible to press and harden it into As the heat conducting material, for example, carbon fiber, carbon bead, SiC bead, metal bead, polymer bead, polymer fiber, or the like is used. As the metal beads, for example, metal beads such as Cu, Ag, Ni, Ci—Cr, Al, Fe, or stainless steel are used. Moreover, you may use the material which processed metal sheets, such as a graphite sheet or aluminum, as a heat conductive material.

The supply pipe 15 connects the storage 11 and the heater 12, and distributes NH ₃ between the storage 11 and the heater 12. That is, the supply pipe 15 forms a supply flow path in which NH ₃ moves between the storage 11 and the heater 12. The valve 16 is disposed in the supply pipe 15. That is, the valve 16 is disposed between the storage 11 and the heater 12. The valve 16 opens and closes the NH ₃ flow path between the storage 11 and the heater 12. For example, the valve 16 is an electromagnetic on-off valve. Opening control and closing control of the valve 16 are performed by a controller (not shown).

In the chemical heat storage device 10 as described above, when the temperature of the exhaust is lower than the warm-up start temperature, the valve 16 is opened, so that NH ₃ accommodated in the storage 11 is supplied to the heater 12 through the supply pipe 15, The reaction material 14 (for example, MgBr ₂ ) of the heater 12 chemically reacts with NH _3, and heat is generated from the reaction material 14. That is, a reaction from the left side to the right side (exothermic reaction) in the following reaction formula (A) occurs. The heat exchanger 4 is heated by the heat generated by the heater 12, and the exhaust gas is heated via the heat exchanger 4.
Mg (NH ₃ ) _X Br ₂ + YNH ₃ ＭｇMg (NH ₃ ) _{x + Y} Br ₂ (A)

When a predetermined time elapses after the valve 16 is opened, or when the temperature of the exhaust gas from the engine 2 becomes equal to or higher than the predetermined temperature, the valve 16 is closed, and the warm-up during the operation of the engine 2 ends. After the warm-up, when the engine 2 enters a steady operation state and the temperature of the exhaust gas discharged from the engine 2 becomes sufficiently high, the heat of the exhaust gas reacts with the heater 23 via the heat exchanger 4 this time. It will be given to the material 14. That is, the reaction material 14 is heated by the exhaust gas through the heat exchanger 4. When the temperature of the exhaust gas becomes equal to or higher than a predetermined recovery temperature, a regeneration reaction in which NH ₃ is desorbed from the reaction material 14 in a state where NH ₃ is chemically adsorbed inside the heater 12 (from the right side in the above reaction formula (A)). Reaction to the left side) occurs. Here, the predetermined recovery temperature is the temperature of the exhaust gas that can give the reaction material 14 heat sufficient to desorb NH ₃ from the reaction material 14. When the NH ₃ from the reaction member 14 detached, the valve 16 is opened, the NH ₃ desorbed from the reaction member 14 is movable from the heater 12 to the storage 11 through the supply pipe 15. When NH ₃ returns to the storage 11, NH ₃ is physically adsorbed by the adsorbent 13 in the storage 11 and collected.

In general, in order to desorb all NH ₃ from the reactant 14 in which NH ₃ is most coordinated (for example, hexahydrate in MgBr ₂ ) to make the NH ₃ non-coordinated reactant 14, NH ₃ must be Compared with the case where NH ₃ is partially desorbed from the maximum coordinated reaction material 14 (eg, hexahydrate in MgBr ₂ ) and NH ₃ becomes a low-coordinate reaction material 14, the energy is very high. Necessary. That is, a high temperature heat source is required to desorb NH ₃ from the reaction material 14. Therefore, normally, the reaction material 14 in which NH ₃ is coordinated to the maximum by causing NH ₃ to be supplied to the reaction material 14 having low NH ₃ coordination (for example, a hydrate in MgBr ₂ ) causes an exothermic reaction. For example, in the case of MgBr ₂ , a hexahydrate), and a reaction material 14 in which NH ₃ is coordinated to the maximum (for example, MgBr ₂ is a hexahydrate) causes heat to cause an elimination reaction, thereby reducing NH _3. coordination of the reaction member 14 (e.g., MgBr in ₂ 2 dihydrate) so as to, and controls the reaction. However, the low-coordinating reaction material 14 has a problem that its melting point is lower than that of the unnatural product due to coordination of NH ₃ . For example, in the case of MgBr ₂ , the melting point of the unnatural product is 700 ° C. or more, whereas in the case of MgBr ₂ , the melting point is lowered to about 400 ° C.

  Next, with reference to FIG. 3, the problem of the deterioration of the heat generation performance in the conventional chemical heat storage device will be described. FIG. 3 is a conceptual diagram showing how particles 19 of the reaction material 14 are melted during a regeneration reaction in a conventional chemical heat storage device. 3A shows the particles 19 of the reaction material 14 at a low temperature, and FIGS. 3B to 3D show how the particles 19 of the reaction material 14 melt at a high temperature.

At a low temperature, as shown in FIG. 3A, the particles 19 of the reaction material 14 are not melted, but the movement of atoms constituting the particles 19 is activated by heat and starts to soften. When heat is applied to the reaction material 14 during the regeneration reaction and the reaction material 14 reaches a high temperature (for example, about 400 ° C.), the particles 19 of the reaction material 14 begin to melt, as shown in FIG. This is because the reaction material 14 is made of a low-coordination (for example, MgBr ₂ dihydrate) material, so that the reaction material 14 has a melting point that is the original melting point of the reaction material 14 (that is, the unnatural reaction material 14). This is because it is lower than the melting point). And when predetermined time passes in such a high temperature state, as shown to (c) of FIG. 3, the contact surface of adjacent particle | grains 19 will join. As a result, the surface area of the bonded surface of each particle 19 is reduced, and the pores serving as NH ₃ diffusion channels are reduced due to blockage or the like. When the time further elapses, as shown in FIG. 3D, the melting of each particle 19 progresses, the joint surface of each particle 19 becomes larger, and the reduction of the pores further proceeds. As described above, when the pores serving as the NH ₃ diffusion flow path decrease due to the melting of the particles 19 of the reaction material 14, the diffusion speed of the NH ₃ supplied to the heater 12 into the reaction material 14 becomes slow. That is, the reaction rate between the reaction material 14 and NH ₃ decreases. As a result, there is a problem that the heat generation performance is lowered.

In response to this problem, in the chemical heat storage device 10 according to the present embodiment, a plurality of particle inclusions 17 having a particle diameter smaller than the particles 19 of the reaction material 14 are interposed between the particles 19 of the reaction material 14. (See FIG. 2). The plurality of particle inclusions 17 are inactive with respect to the reaction material 14 and NH ₃ during the regeneration reaction in which NH ₃ is desorbed from the reaction material 14, and thus do not chemically react with the reaction material 14 and NH ₃ . Further, since the plurality of particle inclusions 17 have a melting point higher than the temperature of the reaction material 14 during the regeneration reaction, the plurality of particle inclusions 17 do not melt even when the reaction material 14 reaches a high temperature during the regeneration reaction. Therefore, even when the reaction material 14 is melted during the regeneration reaction, a plurality of particle inclusions 17 having such an inert and high melting point are interposed between the particles 19 of the reaction material 14. The NH ₃ diffusion channel can be secured by the gap between the particle inclusions 17. Then, when the exothermic reaction after regeneration reaction, the NH ₃ can be reliably supplied by diffusion channel of NH ₃ which is secured by a plurality of particle inclusions 17, it is possible to suppress the reduction of the reaction rate. As a result, it is possible to suppress a decrease in heat generation performance in the chemical heat storage device 10.

  Here, when the addition ratio of the particle inclusions 17 is more than 60 volume percent, the heat capacity of the plurality of particle inclusions 17 themselves increases, so that the heat during the exothermic reaction causes the plurality of particle inclusions 17 themselves. As a result of spending warming, there is a possibility that the effect of suppressing the deterioration of the heat generation performance of the chemical heat storage device 10 cannot be sufficiently achieved. In the chemical heat storage device 10 according to this embodiment, when the addition ratio of the particle inclusions 17 is 60 volume percent or less, such an increase in the heat capacity of the plurality of particle inclusions 17 themselves can be suppressed. Thereby, it becomes possible to reliably exhibit the effect of suppressing the deterioration of the heat generation performance in the chemical heat storage device 10 by the particle inclusions 17.

Furthermore, in the chemical heat storage device 10 according to the present embodiment, when the particle diameter of the particle inclusions 17 is 3 nm or more, a gap through which NH ₃ molecules can pass is easily formed between the particle inclusions 17. It is possible to ensure a NH ₃ diffusion channel.

Furthermore, in the chemical heat storage device 10 according to the present embodiment, when the particle inclusions 17 are SiC, SiO ₂ , or Ni fine particles, SiC, SiO ₂ , or Ni is contained in the reactant 14 and NH ₃ . Since it is inert and has a high melting point with respect to the reaction material 14, any of them is suitable as the particle inclusion 17, and a NH ₃ diffusion channel can be reliably ensured. When the particle inclusions 17 are Ni fine particles or the like, the coefficient of thermal expansion is larger than that of the reaction material 14, so that a gap between the particle inclusions 17 is easily formed by thermal contraction, and the NH ₃ diffusion flow The road can be secured more reliably.

Next, with reference to FIG. 4 and Table 1, an example of an effect of suppressing a decrease in heat generation performance due to the presence of the plurality of particle inclusions 17 between the particles 19 of the reaction material 14 will be described. In this example, MgBr ₂ was used as the reaction material 14, and SiC, SiO ₂ , or Ni powder was used as the particle inclusion 17. In this example, an experiment on heat generation performance was performed as follows.

First, a reaction vessel made of stainless steel having a prismatic opening was filled with MgBr _2, and a lid with an NH ₃ introduction hole was attached to the opening and sealed. Subsequently, after the gas remaining in the internal space of the reaction vessel was removed with a vacuum pump, NH ₃ was introduced to cause an exothermic reaction. After completion of the exothermic reaction, a ceramic heater was brought into close contact with the outside of the reaction vessel, heated to a MgBr ₂ temperature of about 400 ° C., and allowed to stand for 3 hours to cause a regeneration reaction. Note that the emission destination NH ₃ during regeneration reaction of NH ₃ with an empty vessel, was as NH ₃ in a predetermined amount is not too high system pressure even by detachment. Thereafter, NH ₃ was again introduced into the reaction vessel to cause an exothermic reaction, and the exothermic performance was evaluated. The exothermic performance is calculated by measuring the MgBr ₂ temperature with a thermocouple previously installed in the reaction vessel to calculate the peak value of MgBr ₂ temperature during the exothermic reaction (hereinafter also referred to as “exothermic temperature”). The exothermic temperature was used for evaluation. Hereinafter, the exothermic reaction after the regeneration reaction is performed at a high temperature of about 400 ° C. is also referred to as “exothermic reaction after the heat history”.

As a comparative example, first, the above-described experiment was performed without adding the particle inclusion 17 to MgBr ₂ . The result is shown in FIG. FIG. 4 is a graph showing the temperature change during the exothermic reaction of MgBr ₂ when the particle inclusion 17 is not added. The horizontal axis of FIG. 4 shows the elapsed time [s] from the start of introducing NH ₃ into the reaction vessel, and the vertical axis of FIG. 4 shows the temperature of MgBr ₂ . The graph 20b of FIG. 4 shows the temperature change of MgBr ₂ during the exothermic reaction when there is no thermal history as a reference value. The case where there is no thermal history is a case where the regeneration reaction of NH ₃ is caused not in a high temperature state of about 400 ° C. but in a low temperature vacuum. For example, the vacuum is performed so that the temperature of MgBr ₂ becomes a low temperature of about 180 ° C. This is the case where the NH ₃ regeneration reaction is carried out. In this case, since MgBr ₂ is not at a high temperature during the regeneration reaction, the melting of MgBr ₂ does not occur, and as a result, the heat generation performance does not deteriorate due to the melting of MgBr ₂ . As shown in the graph 20b, the heat generation temperature of MgBr ₂ in this case was 260 ° C.

On the other hand, the graph 20a of FIG. 4 shows the temperature change of MgBr ₂ during the exothermic reaction after the thermal history. As shown in the graph 20a, the exothermic temperature of MgBr ₂ was about 237 ° C. In the case of the graph 20a, the response of the exothermic reaction was worse and the exothermic performance was worse than in the case of the graph 20b. This is because the MgBr ₂ melted due to the high temperature of 400 ° C. during the regeneration reaction, the pores serving as the NH ₃ diffusion channel were blocked, and the NH ₃ supply rate during the exothermic reaction was slow. As a result, it has shown that the heat-generation performance fell.

Next, as an example, we were the experiments described above by adding a plurality of particles inclusions 17 to MgBr _2. In Example 1, SiC powder particles having an average particle diameter of 35 nm were used as the particle inclusions 17. In Example 2, as the particle inclusions 17, SiC powder particles having an average particle diameter of 500 nm were used. In Example 3, as the particle inclusions 17, SiO ₂ powder particles having an average particle diameter of 50 nm were used. In Example 4, Ni powder particles having an average particle diameter of 300 nm were used as the particle inclusions 17. In Example 5, as the particle inclusions 17, Ni powder particles having an average particle diameter of 800 nm were used. In each of Examples 1 to 5, the addition ratio of the particle inclusions 17 was 20 volume percent. The results of Examples 1-5 are shown in Table 1 below. Table 1 is a table showing the heat generation performance for each type and addition ratio of the particle inclusions 17. In Table 1, the exothermic temperature of MgBr ₂ during the exothermic reaction after the thermal history is shown as the exothermic performance.

As shown in Table 1, in Example 1, the exothermic temperature of MgBr ₂ during the exothermic reaction after the thermal history was 259 ° C. In Example 2, the exothermic temperature of MgBr ₂ during the exothermic reaction after the heat history was 256 ° C. In Example 3, the exothermic temperature of MgBr ₂ during the exothermic reaction after the heat history was 245 ° C. In Example 4, the exothermic temperature of MgBr ₂ during the exothermic reaction after the heat history was 255 ° C. In Example 5, the exothermic temperature of MgBr ₂ during the exothermic reaction after the heat history was 240 ° C. Therefore, in any of Examples 1 to 5, the exothermic temperature of MgBr ₂ during the exothermic reaction after the heat history was higher than 237 ° C. in the comparative example, and approached the reference value of 260 ° C.

As described above, it has been shown that by adding SiC, SiO ₂ , or Ni powder to MgBr ₂ , it is possible to suppress a decrease in exothermic performance during an exothermic reaction after a thermal history.

Next, with reference to FIG. 5, an example of an effect of suppressing a decrease in heat generation performance when the addition ratio of the particle inclusion 17 is 60 volume percent or less will be described. FIG. 5 is a graph showing changes in the heat generation temperature according to the addition ratio of the particle inclusions 17. The horizontal axis in FIG. 5 indicates the addition rate [vol%] of the particle inclusions 17, and the vertical axis in FIG. 5 indicates the heat generation temperature [° C.] of the reaction material 14. In the graph of FIG. 5, when MgBr ₂ is used as the reaction material 14 and SiO ₂ powder having an average particle diameter of 500 nm is used as the particle inclusion 17, the addition ratio of the SiO ₂ powder is changed. The results of the above experiment are shown.

As shown in FIG. 5, when the addition rate of the particle inclusion (SiO ₂ ) is 60 volume percent or less, the exothermic temperature of the reaction material 14 is higher than 237 ° C. in the comparative example, and the reference value It approached 260 ° C. Therefore, it was shown that when the addition ratio of the particle inclusions 17 is at least 60 volume percent or less, the effect of suppressing the deterioration of the heat generation performance can be surely achieved.

FIG. 5 shows an example in which MgBr ₂ is used as the reaction material 14 and SiO ₂ powder having an average particle diameter of 500 nm is used as the particle inclusion 17. The same applies when at least one of the particle inclusions 17 is of another type, or when the particle size of the particle inclusions 17 is changed.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, You may change in the range which does not change the summary described in each claim, or may apply to others.

  In the said embodiment, although the heater 12 was arrange | positioned around the exhaust pipe 3 so as to correspond to the heat exchanger 4, and it had a cross-sectional annular shape, it is not restricted to this. For example, you may arrange | position a heater so that it may correspond only to a part of heating object. Further, the heater may be arranged at a place other than the outside of the exhaust pipe, for example, may be arranged inside the exhaust pipe in order to heat the exhaust. When a heater is arranged inside the exhaust pipe, for example, a configuration in which a plurality of heaters and a heat exchange unit are alternately stacked, the heat exchange unit is integrated with the heater, and the exhaust is heated by the heater through the heat exchange unit. May be.

  A catalyst coat layer may be formed on part or all of the surface of the heat exchanger 4. In the above embodiment, the heating object is the heat exchanger 4, but the heating object may be another catalyst such as DOC 5 or exhaust gas flowing through the exhaust pipe 3.

  In the said embodiment, although the chemical thermal storage apparatus was applied to the diesel engine 2 which is an internal combustion engine of a vehicle, it is not restricted to this. For example, the chemical heat storage device may be applied to a gasoline engine or the like.

  Further, the chemical heat storage device may be a device that heats a heating target provided other than the exhaust system of the engine. Such a heating target may be various heat media such as engine oil, cooling water, or air. At this time, a heat exchanger may be disposed on the path through which the heat medium flows, and the heat exchanger may be heated by the chemical heat storage device. Further, the chemical heat storage device may be applied to other than the engine.

  DESCRIPTION OF SYMBOLS 10 ... Chemical heat storage apparatus, 11 ... Storage (reservoir), 12 ... Heater (reactor), 14 ... Reactant, 17 ... Particle inclusion, 19 ... Particle | grains.

Claims (4)

A reservoir for storing NH ₃ ;
When heated with heat is generated by a chemical reaction between NH ₃ and reactor with a particulate reactive material desorbed NH _3, and
With
Between the particles of the reaction material, a plurality of particle inclusions having a particle size smaller than the particles of the reaction material are interposed,
The particle inclusions are inert to the reactant and NH ₃ during the regeneration reaction in which NH ₃ is desorbed from the reactant, and have a melting point higher than the temperature of the reactant during the regeneration reaction. A chemical heat storage device.   2. The chemical heat storage device according to claim 1, wherein a ratio of a total volume of the plurality of particle inclusions to a total of a total volume of the reaction material and a total volume of the plurality of particle inclusions is 60 volume percent or less.   The chemical heat storage device according to claim 1 or 2, wherein the particle diameter of the particle inclusion is 3 nm or more. The particle inclusions, SiC, SiO _2, or fine particles of Ni, chemical heat storage device according to any one of claims 1 to 3.