Heat generating structure and heat generating system

Abstract

To properly control the temperature of a heat generating structure while enhancing the safety of a system.SOLUTION: A heat generating structure 120 includes a heat generating material 130 including a hydrogen storage material, and a PTC heater 140 for supplying heat to the heat generating material 130. The PTC heater 140 includes a resistor 141 whose electric resistance increases sharply when reaching the Curie temperature, and electrodes 142, 143 connected to the resistor 141. The operable upper limit temperature Tmax of the PTC heater 140 is set within a range (heat generation appropriate temperature range H1) between a first temperature T1 at which the hydrogen storage material begins to desorb hydrogen, and a second temperature T2 at which the crystal structure of the hydrogen storage material begins to change, and is set so that a temperature rise value due to excessive heat of the heat generating material 130 from the operable upper limit temperature Tmax does not exceed the second temperature T2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a heat generating structure and a heat generating system including a hydrogen storage material.

Background Art

[0002] Conventionally, there is a technique for generating thermal energy using a heat generating material that generates excess heat using hydrogen. For example, based on the temperature measurement results of a heat generating cell that generates heat using a hydrogen storage material, a technique has been proposed for identifying a site that generates excess heat in the heat generating cell and determining the supply position of a hydrogen-based gas supplied into the heat generating cell around that site (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described conventional technology, when a large amount of excess heat is generated in the heat generating cell, the temperature of the entire apparatus may suddenly become abnormally high. For this reason, it is necessary to monitor the temperature inside the apparatus and adjust the temperature of the heat generating cell so that the temperature fluctuation inside the apparatus becomes small. However, if the temperature sensor inside the apparatus or the current control unit of the heater for heating breaks down, such adjustment cannot be performed, the temperature of the entire apparatus may become abnormally high, and there is a risk that the system may undergo thermal runaway.

[0005] An object of the present invention is to appropriately control the temperature of the heat generating structure while enhancing the safety of the system.

Means for Solving the Problems

[0006] One aspect of the present invention is a heat generating structure including a heat generating material containing a hydrogen storage material and a self-controlled heating element that supplies heat to the heat generating material. The self-controlled heating element includes a resistor whose electrical resistance rapidly increases when it reaches the Curie temperature and an electrode connected thereto. The operable upper limit temperature of the self-controlled heating element is set within the range between a first temperature at which the hydrogen storage material starts to desorb hydrogen and a second temperature at which the crystal structure of the hydrogen storage material starts to change, and is set such that the temperature rise value due to the excess heat of the heat generating material from the operable upper limit temperature does not exceed the second temperature.

Advantages of the Invention

[0007] According to the present invention, it is possible to appropriately control the temperature of the heat generating structure while enhancing the safety of the system.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] [First Embodiment] [Configuration Example of Heat Generation System] FIG. 1 is a schematic configuration diagram showing a configuration example of a heat generation system 100. The heat generation system 100 includes a heat energy generation unit 110, a heater power supply unit 150, a hydrogen supply unit 160, an intake and exhaust air volume control unit 170, and a control unit 180. In FIG. 1, for ease of explanation, an example is shown in which the heat generation system 100 includes one heat energy generation unit 110, but it is not limited thereto. For example, the same applies to the case where two or more heat energy generation units are provided. Further, the heat generation system 100 may be composed of a plurality of devices, or may be composed of one device (for example, a heat energy generation device).

[0011] The heat generation system 100 can be mounted on a vehicle and used, for example. When the heat generation system 100 is mounted on a vehicle, it is applicable to various applications that utilize heat, such as warming up and keeping warm the internal combustion engine of a hybrid vehicle, the battery heater of an electric vehicle, warming up and keeping warm the stack of a fuel cell vehicle, etc. Further, it is also applicable to other components and devices mounted on the vehicle, such as air conditioning equipment (air conditioner), components capable of temperature adjustment (steering wheel, seat), etc. In FIG. 1, the components and devices that are the supply destinations of the heat generated in the heat energy generation unit 110 are shown in a simplified manner as target components 191 to 193. In the first embodiment, an example is shown in which heat energy is supplied to three target components 191 to 193, but the first embodiment is also applicable to the case where heat energy is supplied to one, two, or four or more target components.

[0012] The heat energy generation unit 110 includes a housing portion 111 and a heat generation structure 120, and corresponds to a heat generation material system that has a hydrogen storage material and generates excess heat. The heat generation structure 120 includes a heat generation material 130 and a PTC (Positive Temperature Coefficient) heater 140.

[0013] The housing part 111 is for housing the heat generating structure 120 inside, and has a structure that can seal the inside. The housing part 111 is constituted by, for example, a housing that forms a closed space. As the material of the housing part 111, for example, aluminum, iron, or steel can be used.

[0014] A flow pipe (not shown) for circulating the refrigerant is installed on the outer peripheral surface of the housing part 111. This flow pipe is installed so as to communicate the inside and the outside of the housing part 111. Then, the heat generated in the heat generating structure 120 is heat-exchanged with the refrigerant flowing through the flow pipe, and thermal energy is supplied to the target parts 191 to 193 by the refrigerant. Regarding the periphery of the housing part 111, it is preferable to cover the part other than the part in contact with the flow pipe with a heat insulating material so that almost no heat energy radiation or heat convection with the surrounding outside air occurs. Here, an example of installing a flow pipe around the housing part 111 is shown, but the flow pipe may be installed inside the housing part 111. Also, here, an example of performing heat exchange using a flow pipe is shown, but thermal energy may be supplied to the target parts 191 to 193 by other heat transfer means.

[0015] As the refrigerant, a liquid such as water or ethylene glycol can be used. Note that a gas (for example, air) may be used as the refrigerant in addition to the liquid.

[0016] For example, when the heat generating system 100 is used as a heat source for warming up and keeping warm an internal combustion engine, a part of the coolant pipe of the internal combustion engine is provided so as to be in contact with the outer peripheral surface of the housing part 111 as the flow pipe. Thereby, the temperature of the coolant rises by heat exchange with the housing part 111 whose temperature has risen due to the thermal energy generated by the heat generating structure 120, and warming up and keeping warm of the internal combustion engine become possible.

[0017] In the heat energy generation unit 110, a temperature sensor (not shown) and a pressure sensor (not shown) are installed. The temperature sensor is installed in the accommodation unit 111 and is a sensor for detecting the temperature inside the accommodation unit 111. The pressure sensor is installed in the accommodation unit 111 and is a sensor for detecting the pressure inside the accommodation unit 111. Note that the pressure sensor and the temperature sensor are arranged such that their detection parts face the inside of the accommodation unit 111 respectively.

[0018] [Configuration Example of Heat Generation Structure] FIG. 2 is a cross-sectional view schematically showing a configuration example of the heat generation structure 120. In FIG. 2, an example is shown in which the heat generating material 130 is composed of sheet-like heat generating materials 131 and 132, and the sheet-like PTC heater 140 is laminated so as to be sandwiched between the sheet-like heat generating materials 131 and 132. The configurations of the heat generating material 130 and the PTC heater 140 are not limited to sheet-like shapes, and other shapes may be used.

[0019] The PTC heater 140 is a heating device that heats the heat generating material 130 and supplies heat to the heat generating material 130. Here, the PTC heater 140 is mainly a ceramic material mainly composed of barium titanate (BaTiO3), and its electrical resistance increases rapidly when it reaches near the Curie temperature (Tc). The Curie temperature of the PTC heater 140 changes by performing Ba, Ca, Sr, Pb, Y substitution. Note that as other materials for the PTC heater 140, there are bismuth oxide-based ceramic materials with a higher operable upper limit temperature. In addition, when the temperature of the PTC heater 140 increases, its electrical resistance rapidly increases due to changes in the crystal structure and electronic structure of the constituent materials, and the current stops flowing, so its self-heating is suppressed. For this reason, the PTC heater 140 can be called a self-controlled heating element. In addition, as long as the composition of the material itself constituting the PTC heater 140 does not change and the crystal structure and electronic structure do not change (excluding mechanical damage such as applying stress), the characteristics of self-controlled heating do not deteriorate and it does not malfunction.

[0020] Specifically, the PTC heater 140 includes a resistor 141 whose electrical resistance rapidly increases when it reaches the Curie temperature, and electrodes 142 and 143 arranged so as to sandwich the resistor 141. Also, in the first embodiment, the maximum value of the temperature at which the PTC heater 140 can stably rise to the maximum is described as the operable upper limit temperature Tmax.

[0021] The heat generating material 130 is a heat generating material having a hydrogen storage function and is arranged on the surface of the PTC heater 140. This heat generating material is also referred to as a hydrogen storage material. Note that the hydrogen storage material is a hydrogen storage alloy or a material containing a hydrogen storage alloy that continuously generates excess heat energy with respect to the energy used for heating when heated in a state where hydrogen is supplied. By using the hydrogen storage material, excess heat energy can be continuously generated, so that the heat energy supplied to the material to promote the hydrogen storage and desorption reaction can be efficiently recovered. Hereinafter, an example of the configuration example and manufacturing method of the hydrogen storage material (heat generating material 130) will be shown.

[0022] [Hydrogen storage material] The hydrogen storage material of the present embodiment contains at least two types of metals. Here, among the two types of metals, the one with the lower melting point is referred to as the first metal, and the one with the higher melting point is referred to as the second metal. It is essential that the melting point of the first metal is 230°C or higher. Also, among the first metal and the second metal, at least one has a hydrogen solubility greater than that of copper and a standard formation enthalpy less than that of calcium hydride at a temperature equal to or higher than the melting point of the first metal and lower than the melting point of the second metal. Note that the value of the hydrogen solubility for a certain metal may be a value obtained experimentally or a value obtained by calculation using computer simulation.

[0023] Furthermore, at least one of the hydrides of the first metal or the second metal has a standard enthalpy of formation equal to or higher than that of CaH₂ (-186.2 kJ / mol). This ensures that when the hydrogen storage material generates a large amount of heat, the hydrogen desorption for the repeated phase transition of the hydrogen compound alloy is sufficiently carried out. Note that the value of the standard enthalpy of formation of a metal hydride may also be an experimentally determined value or a value obtained by calculation using computer simulation.

[0024] When at least one metal satisfying the definition of these first and second metals is included, it can be used as the hydrogen storage material in this embodiment. That is, even if three or more metals are included, it can be used when two of them satisfy the above definition. Also, there are no particular restrictions on the form of inclusion of these metals. However, it is preferable that the first metal and the second metal exist in the state of an alloy having a plurality of phases with different composition ratios.

[0025] There are no particular restrictions on the specific types of the first metal and the second metal, and they can be arbitrarily selected from combinations that can satisfy the above regulations. Whether a certain metal corresponds to the first metal or the second metal is a relative matter determined by its relationship with other metals to be combined. Therefore, depending on the combination of these metals, there are possibilities for a certain metal to correspond to either the first metal or the second metal. As an example, the first metal includes aluminum (Al), tin (Sn), and lead (Pb). Also, the second metal includes nickel (Ni), titanium (Ti), zirconium (Zr), manganese (Mn), zinc (Zn), vanadium (V), and calcium (Ca). Using these metals is preferable because it is possible to form a hydrogen storage material with a large calorific value. From the perspective that it can function even when the heating temperature is relatively low, it is preferable to use tin (Sn) with a relatively low melting point as the first metal. Also, from the perspective of a large calorific value, it is preferable to use aluminum (Al) as the first metal. Furthermore, examples of the "first metal - second metal" combination include nickel - zirconium, aluminum - nickel, aluminum - titanium, aluminum - manganese, aluminum - zinc, tin - titanium, aluminum - calcium, etc. From the perspective that it is particularly possible to form a hydrogen storage material with a large calorific value, the combinations of aluminum - nickel, aluminum - titanium, and tin - titanium are preferable, the combinations of aluminum - nickel and tin - titanium are more preferable, and the combination of aluminum - nickel is particularly preferable. Of course, other combinations may also be used.

[0026] [Method for manufacturing hydrogen storage material] There are no particular restrictions on the method for manufacturing the hydrogen storage material used in this embodiment, and it can be manufactured by referring to the common general knowledge of conventionally known technologies (for example, WO2020 / 080303). As an example, the case of using aluminum as the first metal and nickel as the second metal will be described.

[0027] First, prepare aluminum powder and nickel powder. The shape of the metal does not necessarily have to be powder, but in terms of uniform mixing, it is desirable to be in powder form. Weigh the two types of powders in a desired ratio and mix them using a mortar and pestle. The material of the mortar and pestle can be any material such as agate or alumina.

[0028] Subsequently, perform heat treatment on the composite particles obtained above to alloy them. Note that it is not necessarily required to alloy them in advance, and alloying may also be performed during the firing after coating on the surface of the heater. The method of alloying is not limited to heat treatment only, and may also be chemical alloy plating or mechanical alloying using a ball mill device to mechanically mix them.

[0029] When adjusting the particle size of the alloy after alloying, the particle size may be reduced by grinding or the like.

[0030] [Configuration Example of Heat Generation System] Returning to FIGS. 1 and 2, the heater power supply unit 150 is a power source that supplies a constant voltage to the PTC heater 140 based on an instruction from the control unit 180 and has an on / off function by a switch. In this embodiment, since the PTC heater 140 is used, a constant voltage power supply that directly passes a current through the PTC heater 140 is connected to the electrodes 142 and 143, and a configuration is adopted in which a current is passed through the PTC heater 140 by the on / off function of the switch. Note that, as the heater power supply unit 150, for example, a constant voltage power supply circuit can be used. Also, when this system is mounted on a vehicle, an in-vehicle power supply is used as the heater power supply unit 150. On the other hand, when this system is for stationary use, a power supply for the PTC heater is used as the heater power supply unit 150.

[0031] The hydrogen supply unit 160 is a hydrogen gas supply device that supplies hydrogen (H2) to the exothermic material 130 via a supply pipe. The hydrogen supply unit 160 also includes a hydrogen tank filled with hydrogen gas, a pump for supplying the hydrogen gas to the accommodation unit 111, piping, and the like. Hydrogen (H2) is for being occluded in the exothermic material when the exothermic material 130 is heated to cause an exothermic reaction. Hydrogen (H2) may be held in the tank in the state of hydrogen gas, or may be a gas generated as needed by reforming, for example, methanol or biomass. Note that instead of the hydrogen tank, a tank for holding ethanol or biomass and a reformer may be provided to generate hydrogen gas as needed by reforming.

[0032] The supply and exhaust amount control unit 170 adjusts the supply amount of hydrogen supplied to the exothermic material 130 based on an instruction from the control unit 180. As the supply and exhaust amount control unit 170, for example, a flow rate adjustment valve interposed in the supply pipe for supplying hydrogen gas from the hydrogen supply unit 160 to the exothermic material 130, a vacuum (suction) pump for recovering excess gas in the accommodation unit 111, or the like can be used. Also, as the supply and exhaust amount control unit 170, a purge valve connected to a purge pipe that communicates the inside and the outside of the accommodation unit 111 and is used to adjust the pressure inside the accommodation unit 111 can be used. Then, when the purge pipe is opened and closed by the purge valve, the pressure inside the accommodation unit 111 is adjusted.

[0033] The control unit 180 controls each part of the heat energy generation unit 110 to control the operating state of the heat energy generation unit 110. When starting the PTC heater, the control unit 180 performs control to turn on the power, and when stopping the PTC heater, turns it off. Note that the control unit 180 is composed of one or more microcomputers including a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

[0034] Specifically, the control unit 180 controls the air supply and exhaust amount control unit 170 to supply hydrogen from the hydrogen supply unit 160 to the storage unit 111, and supplies power from the heater power supply unit 150 to the PTC heater 140 to continuously heat the heat generating material 130, and controls the temperature of the storage unit 111 to rise and the heat generating material 130 to start the hydrogen occlusion and desorption reaction so as to generate excessive heat energy. Further, the control unit 180 controls the air supply and exhaust amount control unit 170 to adjust the pressure, monitors the detected value of the pressure inside the storage unit 111 with a pressure sensor, and when it reaches a state where excessive heat energy is stably generated, controls the air supply and exhaust amount control unit 170 to fix these pressure conditions. In this embodiment, the PTC heater 140 stops the current flow due to the increase in resistance at a temperature equal to or higher than the operable upper limit temperature Tmax, and the PTC heater 140 itself performs temperature control. Note that whether or not it has reached a state where excessive heat energy is stably generated may be determined as needed according to the requirements of the heat energy supply destination, and is not particularly limited. For example, it can be based on the fluctuation range of the calorific value of the heat generating material 130 falling within a predetermined range of the control target value by the control unit 180. The predetermined range of the control target value can be in the range of -9% to +9% of the control target value. Preferably, it is in the range of -7% to +7% of the control target value, and more preferably, it is in the range of -5% to +5% of the control target value.

[0035] In this way, the control unit 180 controls the air supply and exhaust amount control unit 170 based on the pressure information from the pressure sensor, thereby adjusting the pressure in the storage unit 111 and controlling the calorific value of the heat generating material 130. That is, by controlling the calorific value of the heat generating material 130, the control unit 180 controls the operating state of the heat energy generation unit 110. In this way, the control unit 180 maintains the operating conditions of the heat generating material system that continues to operate by controlling the operating state of the heat energy generation unit 110. Note that the operating state and non-operating state of the heat energy generation unit 110 will be described with specific examples of the heat generating material and operating conditions described later.

[0036] In this embodiment, the operating state of the heat energy generation unit 110 is controlled by the control unit 180. However, another control device may be provided inside or outside the heat generation system 100, and the operating state of the heat energy generation unit 110 may be controlled by that control device. For example, when this system is mounted in a vehicle, the controller provided in the vehicle may function as a part of the control unit 180.

[0037] [Specific Examples of Heat Generation Materials and Operating Conditions] As described above, as the heat generation material (hydrogen storage material) of this embodiment, one containing at least two kinds of metals can be used. Here, an example of a heat generation material having a hydrogen storage function capable of generating heat energy stably and oscillating in a time series manner is shown together with an example of conditions (pressure, temperature, etc.) for operating (hydrogen storage reaction) the heat generation material system. Note that the example shown here is just an example for realizing this embodiment and is not limited thereto.

[0038] [Configuration Example of Heat Generation Material] The heat generation material is formed from a hydrogen storage alloy. This hydrogen storage alloy releases a very large amount of heat to the outside when heated in the presence of hydrogen gas (H2). Such a hydrogen storage alloy is suitably applied to a heat energy generation system as a heat generation material. Further, in the heat generation material according to this embodiment, a phase transition of the alloy occurs by desorbing the stored hydrogen. As a result of the repetition of the phase transition due to the absorption and desorption of hydrogen, excess heat is generated.

[0039] Note that the mechanism by which the heat generation material according to this embodiment can generate a very large amount of heat (excess heat) is not completely clear. However, the inventors of the present invention presume that, regarding the above mechanism, as a result of the repetition of the phase transition of the hydride alloy due to the repetition of the absorption and desorption of hydrogen, a large amount of heat generation as described above occurs.

[0040] The heat generation material of this embodiment is not particularly limited as long as it can generate excess heat in the presence of hydrogen gas, but a palladium (Pd)-nickel (Ni)-zirconium (Zr) system can be exemplified.

[0041] A hydrogen storage alloy of the palladium (Pd)-nickel (Ni)-zirconium (Zr) system is produced by subjecting a palladium (Pd)-nickel (Ni)-zirconium (Zr) alloy to melt spinning (melt quenching) to form an amorphous ribbon, then performing an oxidation treatment in the atmosphere, and further performing a pulverization treatment. The melt spinning method is a method of obtaining an amorphous ribbon by spraying a high-temperature molten alloy onto the surface of a rapidly rotating copper roll, thereby quenching it in a time much shorter than the crystallization time. By subjecting the amorphous ribbon to an oxidation treatment, ZrO2 in which the constituent element zirconium (Zr) is oxidized is generated, and a fine structure in which palladium (Pd) and nickel (Ni) are precipitated as nano metal particles is formed.

[0042] As an example of a hydrogen storage alloy of the palladium (Pd)-nickel (Ni)-zirconium (Zr) system, an alloy prepared at an atomic ratio of palladium (Pd):nickel (Ni):zirconium (Zr) = 4:31:65 using the melt spinning method is fired in air at 450 °C for 60 hours, whereby a heat generating material having a plate shape with a thickness of about 35 μm and a length of 30 to 300 μm can be prepared.

[0043] [Examples of operating (reaction) conditions] Next, conditions for operating a heat energy generation system (corresponding to the heat generation system 100) using the hydrogen storage alloy will be described.

[0044] <First step> First, in the heat energy generation system, the hydrogen storage alloy is heated and depressurized with respect to the reference temperature and reference pressure to remove impurities on the surface of the hydrogen storage alloy. The reference temperature and reference pressure are so-called normal temperature and normal pressure. For example, the reference temperature can be 25 °C and the reference pressure can be 0.1 MPa (about 1 atm).

[0045] To describe the first step in more detail, pretreatment (vacuum degassing and heat desorption) is performed on the hydrogen storage alloy to remove impurities from the alloy surface. This pretreatment is carried out by heating and reducing the pressure with respect to the reference temperature and reference pressure. The temperature during this heating is not particularly limited, but for example, it is about 200°C. Also, the pressure during pressure reduction is not particularly limited, but for example, it is a vacuum (on the order of 1.0×10-2 Pa). The time for maintaining heating and pressure reduction is not particularly limited either, but for example, it is 50 to 100 minutes. In the case of a palladium (Pd)-nickel (Ni)-zirconium (Zr) based hydrogen storage alloy, it is 200°C and a vacuum (0.01 Pa). Since the heating temperature is different from the operating reference temperature in the third step described later, heat is applied to the heat energy generation part from the outside such as a heating furnace (not shown). At this time, using a temperature sensor, the heat applied is adjusted so that the internal temperature of the heat energy generation part becomes the aforementioned heating temperature.

[0046] <Second Step> Next, the gas phase part of the system (corresponding to the housing part 111) containing the hydrogen storage alloy and hydrogen gas is heated and pressurized to a first set temperature higher than the reference temperature and a first set pressure higher than the reference pressure to perform hydrogen storage in which hydrogen is stored in the alloy phase of the hydrogen storage alloy. Here, the gas phase part of the system means the space where hydrogen gas exists inside the housing part 111.

[0047] Here, since the first set temperature and the first set pressure vary depending on the hydrogen storage alloy used, they are not particularly limited. However, the first set temperature is, for example, 400 to 800 °C, and the first set pressure is higher than, for example, 0.1 MPa(abs) (about 1 atm) and is in the range of 1 MPa(abs) (about 10 atm) or less. The time for maintaining the first set temperature and the first set pressure is not particularly limited because it varies depending on the hydrogen absorption rate characteristics of the hydrogen storage alloy used, but is, for example, 1 to 60 hours. In the case of a palladium (Pd)-nickel (Ni)-zirconium (Zr)-based hydrogen storage alloy, it is 500 to 800 °C and more than 0.1 to 1 MPa. Similar to the first step, since the heating temperature is different from the operating reference temperature in the third step described later, heat is applied to the heat energy generation part from the outside such as a heating furnace (not shown). At this time, using a temperature sensor, the heat applied is adjusted so that the internal temperature of the heat energy generation part becomes the aforementioned heating temperature.

[0048] <Third Step> Next, a process for surely causing the vibration heat generation phenomenon is performed. Specifically, a process of maintaining the gas phase part of the system containing the hydrogen storage alloy and hydrogen gas at an operating reference temperature higher than the reference temperature and lower than the first set temperature and at an operating reference pressure lower than the first set pressure is performed.

[0049] Here, since the operating reference temperature and the operating reference pressure vary depending on the hydrogen storage alloy used, they are not particularly limited. However, the operating reference temperature is, for example, 200 to less than 800 °C (however, it is lower than the first set temperature), and the operating reference pressure is, for example, 0.01 MPa(abs) (about 0.1 atm) to 0.3 MPa(abs) (about 3 atm) (however, it is lower than the first set pressure). Note that even when the operating reference temperature and the operating reference pressure are maintained, although the vibration amplitude gradually decreases with the passage of time, the vibration heat generation continues for a predetermined time (for example, about 100 hours). In the case of a palladium (Pd)-nickel (Ni)-zirconium (Zr)-based hydrogen storage alloy, it is 450 °C and 0.01 MPa. Note that as the range of the operating reference temperature, for example, 20 °C to 900 °C may be set, or 100 °C to 700 °C may be set. Further, preferably, 200 °C to 500 °C can be set.

[0050] In this way, in the heat energy generation system, by performing each process from the first step to the third step, it becomes possible to surely generate excess heat that is generated pulsatively.

[0051] Further, the control device (corresponding to the control unit 180) of the heat energy generation system maintains the gas phase part of the system in the atmosphere of the conditions shown in the second step for a predetermined time or more, and then until the heat generation amount per unit mass of the heat generating material starts to vibrate with an amplitude equal to or greater than the threshold value, it executes control to maintain the gas phase part of the system in the atmosphere of the conditions shown in the third step.

[0052] Here, the operating state and non-operating state of the heat energy generation unit (corresponding to the heat energy generation unit 110) will be described.

[0053] Regarding each process from the first step to the third step described above, for example, it is performed once at the time of factory shipment (for example, when inspecting whether the heat energy generation system can operate properly).

[0054] And when operating the heat energy generation system, it is started from room temperature, omitting the above-described first step and second step, and performing the process of the above-described third step. That is, at the time of factory shipment or the like, by performing each process from the first step to the third step once, hydrogen gas is occluded in the heat generating material and remains, so a new occlusion step becomes unnecessary. Therefore, when operating the heat energy generation system, by performing only the process of the above-described third step, the heat energy generation system can be quickly started up.

[0055] Also, in the thermal energy generation system, when activating the non-operating thermal energy generation unit, hydrogen gas is supplied and the PTC heater is powered on to apply heat, and control is performed so that the temperature and pressure of the thermal energy generation unit reach the operating reference temperature and operating reference pressure shown in the third step. That is, the intake and exhaust air volume control unit controls to maintain the pressure of the gas phase part of the thermal energy generation unit at the operating reference pressure, and the PTC heater with the operable upper limit temperature set within the range of the first temperature and the second temperature operates to adjust the heat supply so as to maintain the temperature of the gas phase part of the thermal energy generation unit at the operating reference temperature, whereby the non-operating thermal energy generation unit can be brought into an operating state. Thereby, it becomes possible to control the non-operating thermal energy generation unit to be an operating thermal energy generation unit that stably generates oscillatory heat generation.

[0056] Also, in the thermal energy generation system, when setting the operating thermal energy generation unit to a non-operating state, the supply of hydrogen gas is stopped and the power supply of the PTC heater is turned off to stop the heat supply. In this example, an example of stopping the supply of hydrogen gas and the heat supply from the PTC heater is shown, but one of these may be stopped or adjusted to set the thermal energy generation unit to a non-operating state. That is, the thermal energy generation unit can be set to a non-operating state by lowering the temperature or reducing the pressure of the gas phase part of the operating thermal energy generation unit.

[0057] In this way, in the present embodiment, instead of changing the amount of thermal energy generated by performing complex hydrogen gas supply control, temperature control, and pressure control each time according to the external thermal energy demand amount, it is possible to continuously generate thermal energy at the most efficient temperature and pressure set at startup.

[0058] [Example of temperature transition of heat generation structure] FIG. 3 is a diagram showing an example of the temperature transition of the heat generation structure 120. In the graph shown in FIG. 3, the horizontal axis represents the time axis, and the vertical axis represents the temperature.

[0059] The temperature T1 indicates the temperature at which the hydrogen occluded in the exothermic material 130 starts to desorb. That is, when the temperature of the exothermic material 130 drops below the temperature T1, the occluded hydrogen stops desorbing, and thus the exothermic material 130 stops generating excess heat.

[0060] The temperature T2 indicates the temperature at which the crystal structure of the hydrogen storage material of the exothermic material 130 starts to change. That is, when the temperature of the exothermic material 130 exceeds the temperature T2, the crystal structure of the exothermic material 130 may break, and the exothermic material 130 may no longer be able to generate excess heat.

[0061] Therefore, by setting the temperature of the exothermic material 130 within the range between the temperature T1 and the temperature T2, the exothermic material 130 can efficiently generate excess heat. In this embodiment, the range between the temperature T1 and the temperature T2 is referred to as the appropriate exothermic temperature region H1. For example, for a zirconium (Zr)-nickel (Ni) alloy, the lower limit value (temperature T1) range (desorption temperature range) of the appropriate exothermic temperature region H1 is 80 to 430 °C, and the lowest temperature is 80 °C (see "Structural Changes and Crystallization Processes during Hydrogen Absorption and Release of Amorphous Zr-Ni Alloys" by Kiyoshi Aoki and Ken Masumoto, Transactions of the Japan Institute of Metals, Vol. 49, No. 1 (1985), pp. 89-96). Also, when the composition of the zirconium (Zr)-nickel (Ni) alloy is (Zr:Ni = 67:33 mol%), the upper limit value (temperature T2) of the appropriate exothermic temperature region H1 is 1000 °C.

[0062] In addition, the temperature Tmax indicates the operable upper limit temperature of the PTC heater 140. Also, the range from the temperature Tmax to the temperature T2 is defined as the temperature rise region H2. H2 means the region where the temperature rises due to the excess heat generated from the exothermic material 130 with respect to the temperature Tmax as a reference.

[0063] As shown by the curve L1, the temperature of the heat generating structure 120 rises due to heating by the PTC heater 140 until the temperature of the heat generating structure 120 reaches the temperature T1. Further, when the temperature of the heat generating structure 120 exceeds the temperature T1, the hydrogen occluded in the heat generating material 130 starts to be desorbed, so that excess heat is generated, and thus the temperature of the heat generating structure 120 exceeds the operable upper limit temperature Tmax of the PTC heater 140. By setting the temperature of the heat generating material 130 within the range between the temperature T1 and the temperature T2, the heat generating material 130 can efficiently generate excess heat.

[0064] Here, the energy consumption efficiency COP (Coefficient Of Performance) of the heat generating structure 120 is obtained by the following formula. In this embodiment, COP > 1. COP = Output energy (W) from the heat generating material 130 / Input energy (W) from the PTC heater 140

[0065] Further, the output energy from the heat generating material 130 is obtained by the following excess heat conversion formula. Output energy (W) from the heat generating material 130 = m (weight of the heat generating material 130) × c (specific heat of the heat generating material 130) × ΔT (temperature rise range due to excess heat generated from the heat generating material 130)

[0066] Note that the temperature rise range ΔT means the temperature rise range of the temperature rising due to the excess heat generated from the heat generating material 130 when based on the temperature Tmax.

[0067] According to the above-described excess heat conversion formula, if the output energy from the heat generating material 130, the weight of the heat generating material 130, and the specific heat of the heat generating material 130 are known, the temperature rise range ΔT due to the excess heat generated from the heat generating material 130 can be calculated. By setting the operable upper limit temperature Tmax of the PTC heater 140 so that the temperature rise range ΔT calculated in this way is within the range of the temperature rising region H2, the safety of the system can be improved.

[0068] Here, a case where a heater other than the PTC heater is used is set as a comparative example. In this case, during normal operation, it is necessary to control the temperature of the heater by adjusting the current in the heater control unit based on the temperature inside the heat energy generation unit acquired by the temperature sensor so that the heat energy generation unit continues to generate heat at a constant output. That is, the temperature of the heater is controlled by adjusting the current so that the temperature of the heat energy generation unit falls within the appropriate heat generation temperature range H1. Also, in this comparative example, when a thermal runaway state occurs in which excessive heat is generated in large quantities in the heat energy generation unit, it is necessary for the heater control unit to control the heater so that the temperature of the heat energy generation unit does not rise.

[0069] In this comparative example, if the temperature sensor or the heater control unit fails, the heater cannot be controlled, the temperature of the heat energy generation unit exceeds temperature T2 and goes outside the appropriate heat generation temperature range H1, and thermal runaway may occur due to the sudden heat generation of the material. In this case, there is a risk that the heat energy generation unit will reach an abnormally high temperature and the devices of the heat generation system will fail.

[0070] Therefore, in the present embodiment, a PTC heater 140 is used as the heater for heating the heating material 130. By using the PTC heater 140, since a temperature sensor for the heater and a heater control unit for adjusting the current are not used, the failure rate of the sensor and the heater control unit can be reduced. Also, since the temperature control is performed by the PTC heater 140 itself, it is possible to prevent the heat generation system 100 from reaching an abnormally high temperature and improve the safety of the system.

[0071] Specifically, a PTC heater 140 for which the appropriate heat generation temperature range H1 > ΔT holds is used so that the temperature of the heat generation structure 120 falls within the appropriate heat generation temperature range H1. More preferably, a heating material 130 and a PTC heater 140 that satisfy the following conditions (1) and (2) are used. Condition (1) Tmax > T1, Condition (2) T2 > Tmax + ΔT

[0072] More specifically, in order for the heat energy generation unit 110 to continuously generate heat at a constant output, it is preferable that the operable upper limit temperature Tmax be the median value (or a value slightly higher than the median value) of the appropriate heat generation temperature range H1. The median value shown here includes not only the strictly central value but also the median value and values in its vicinity. Note that the relationship between Tmax1 shown in the second embodiment and the median value of the appropriate heat generation temperature range H1 is the same. Also, as shown by the curve L1, in the operating state of the heat energy generation unit 110, the temperature of the excess heat by the heat generating material 130 is preferably above the operable upper limit temperature Tmax, that is, the curve L1 preferably operates while vibrating slightly above the operable upper limit temperature Tmax.

[0073] [Examples and Comparative Examples] Next, examples and comparative examples of the heat generating structure will be described.

[0074] [Configuration Examples of Heat Generating Structure] FIG. 4 is a cross-sectional view showing the heat generating structure 200 used in the first to fourth embodiments and the first to third comparative examples. The heat generating structure 200 is configured by laminating, on a plane, sheet-like heat generating materials 210a and 210b, a sheet-like PTC heater 220, and sheet-like meshes 211a and 211b in an accommodating portion 201. The accommodating portion 201 is a hollow container that accommodates the heat generating structure 200. For example, it may be created by machining SUS (stainless steel), or a pipe or cylinder-shaped container may be diverted. Note that the fourth embodiment and the third comparative example are shown in the second embodiment.

[0075] As the heat generating materials 210a and 210b, pellets obtained by roughly solidifying zirconium (Zr)-nickel (Ni) powder are filled. Also, the heat generating material 210a is held by the mesh 211a, and the heat generating material 210b is held by the mesh 211b. The meshes 211a and 211b are sheet-like meshes for holding the heat generating materials 210a and 210b, and a space is formed inside. Due to this space, ventilation holes 212a and 212b are formed inside the heat generating materials 210a and 210b. In the ventilation holes 212a and 212b, hydrogen gas flows as shown by the arrow 251a and the like.

[0076] The PTC heater 220 includes a resistor 221 and electrodes 222 and 223 arranged so as to sandwich the resistor 221. Further, the PTC heater 220 is fixed in contact with the container of the housing portion 201.

[0077] A hydrogen injection valve 232 for adjusting hydrogen supplied from a hydrogen supply source via a supply pipe 231 is connected to the housing portion 201. Further, a purge valve 241 for adjusting the pressure inside the housing portion 201 using a purge pipe 242 is connected to the housing portion 201.

[0078] Further, a pressure sensor and a temperature sensor are installed inside the housing portion 201. Then, the pressure inside the housing portion 201 is measured by the pressure sensor, and the temperature inside the housing portion 201 is measured by the temperature sensor.

[0079] [Method for Measuring Total Heat Generation Energy] Here, 30 mg of a nickel (Ni)-zirconium (Zr) alloy was measured for the heat generation amount by DSC measurement using a DSC (Differential scanning calorimetry) measurement device. In this measurement, 450 °C was set as the operating reference temperature and 0.01 MPa (0.1 atm) was set as the operating reference pressure. In this measurement, a heat generation amount of 100 mW / g could be obtained, so the heat generation amount obtained according to the conditions (sample weight, temperature) of each example and comparative example was estimated by conversion. Further, since the DSC measurement device can maintain the temperature in the same manner as the PTC heater, it was converted on the assumption that heat is generated under the same conditions as the PTC heater.

[0080] Further, in the first to fourth examples and the first to third comparative examples, an example is shown in which stainless steel is used for the housing portion, aluminum is used for the electrodes, and a variable voltage power supply is used for the voltage application circuit.

[0081] <First Example> [Configuration of Heat Generation Structure] Heat generation material: Pellet obtained by solidifying zirconium (Zr)-nickel (Ni) powder, Resistor: (Ba0.996 Y 0.004 )TiO3 [Implementation conditions] Tmax: around 300 °C, T1 = 80 °C, T2 = 1000 °C, weight of the heating material: 200 g, specific heat of the heating material: 0.37 J / (g·°C) [Measurement results] Heat generation amount: 13 W

[0082] In the first embodiment, since Tmax is within the range of the appropriate heat generation temperature region H1, appropriate excess heat can be generated, and stable heat energy can be generated.

[0083] Next, the first comparative example shows an example where the weight of the heating material is less than that in the first embodiment. Also, the second comparative example shows an example where Tmax is set below the lower limit value (temperature T1) of the appropriate heat generation temperature region H1.

[0084] <First Comparative Example> [Configuration of the heat generating structure] Heating material: pellets made of zirconium (Zr)-nickel (Ni) powder, resistor: Bi4Ti3O9 [Implementation conditions] Tmax = around 675 °C, T1 = 80 °C, T2 = 1000 °C, weight of the heating material: 10 g, specific heat of the heating material: 0.37 J / (g·°C)

[0085] In the first comparative example, although excess heat could be generated, since the weight of the heating material was small, the generated energy gradually weakened over time and stable heat energy could not be generated.

[0086] <Second Comparative Example> [Configuration of the heat generating structure] Heating material: pellets made of zirconium (Zr)-nickel (Ni) powder, resistor: (Ba 0.7 Sr 0.3 )TiO3 [Implementation conditions] Tmax = around 70 °C, T1 = 80 °C, T2 = 1000 °C, weight of the heating material: 200 g, specific heat of the heating material: 0.37 J / (g·°C)

[0087] In Comparative Example 2, since Tmax (around 70°C) is lower than the lower limit value (temperature T1 = 80°C) of the appropriate heat generation temperature range H1, it cannot be heated up to the temperature at which the hydrogen occluded in the heat generating material starts to desorb. Therefore, hydrogen cannot be desorbed and no excess heat is generated.

[0088] In the second embodiment, an example is shown in which Tmax is set above the appropriate heat generation temperature range H1 compared to the first embodiment. In the third embodiment, an example is shown in which Tmax is set below the appropriate heat generation temperature range H1 compared to the first embodiment.

[0089] <Second Embodiment> [Configuration of Heat Generation Structure] Heat generating material: Pellets made by compacting zirconium (Zr)-nickel (Ni) powder, Resistor: Bi4Ti3O9 [Implementation Conditions] Tmax = around 675°C, T1 = 80°C, T2 = 1000°C, Weight of heat generating material: 200 g, Specific heat of heat generating material: 0.37 J / (g·°C) [Measurement Results] Heat generation amount: 30 W

[0090] In the second embodiment, the temperature of the heat generation structure 200 did not reach the upper limit (1000°C) of the appropriate heat generation temperature range H1, and heat energy could be stably generated. Also, since Tmax was set above the appropriate heat generation temperature range H1 compared to the first embodiment, more heat energy could be generated than in the first embodiment.

[0091] <Third Embodiment> [Configuration of Heat Generation Structure] Heat generating material: Pellets made by compacting zirconium (Zr)-nickel (Ni) powder, Resistor: BaTiO3 [Implementation Conditions] Tmax = around 150°C, T1 = 80°C, T2 = 1000°C, Weight of heat generating material: 200 g, Specific heat of heat generating material: 0.37 J / (g·°C), [Measurement Results] Heat generation amount: 6.7 W

[0092] In the third embodiment, since the temperature of the heat generating structure 200 rose to a temperature higher than the lower limit (80°C) of the proper heat generation temperature range H1, heat energy could be stably generated.

[0093] [Configuration and Effects of the First Embodiment] The heat generating structure 120 according to the first embodiment includes a heat generating material 130 containing a hydrogen storage material, and a PTC heater 140 (an example of a self-controlled heating element) that supplies heat to the heat generating material 130. The PTC heater 140 includes a resistor 141 whose electrical resistance rapidly increases when it reaches the Curie temperature, and electrodes 142 and 143 connected to the resistor 141. The operable upper limit temperature Tmax of the PTC heater 140 is set within the range (proper heat generation temperature range H1) between a first temperature T1 at which the hydrogen storage material starts to desorb hydrogen and a second temperature T2 at which the crystal structure of the hydrogen storage material starts to change, and is set such that the temperature rise value of the heat generating material 130 due to excessive heat from the operable upper limit temperature Tmax does not exceed the second temperature T2.

[0094] According to this configuration, since the temperature of the PTC heater 140 does not exceed the operable upper limit temperature Tmax, the temperature of the heat generating structure 120 (the temperature obtained by adding the temperature rise range due to excessive heat generated by the heat generating material 130 to the operable upper limit temperature Tmax) can be suppressed below the upper limit value (temperature T2) of the proper heat generation temperature range H1. Also, since the PTC heater itself adjusts the output instead of adjustment based on a temperature sensor, it is possible to prevent failure due to large thermal fluctuations. As a result, it is possible to prevent thermal runaway of the system without depending on a temperature sensor or heater control, appropriately suppress the temperature rise of the heat generating structure 120, and further enhance the safety of the system. That is, while enhancing the safety of the system, the temperature of the heat generating structure 120 can be appropriately controlled.

[0095] In addition, in the heat generating structure 120 according to the first embodiment, when the heat generating structure 120 is in an operating state, the temperature of the gas phase portion of the housing portion 111 that houses the heat generating structure 120 is set as the operating reference temperature, and the pressure of the gas phase portion is set as the operating reference pressure. For example, when using a hydrogen storage alloy of the palladium (Pd)-nickel (Ni)-zirconium (Zr) system, 450 ° C can be set as the operating reference temperature, and 0.01 MPa can be set as the operating reference pressure.

[0096] According to this configuration, by operating at an efficient temperature and pressure, thermal energy can be generated so as to vibrate stably in time series, and the stability of the system can be enhanced. That is, thermal energy is generated stably in time series under efficient operating conditions (gas phase portion pressure and temperature). As a result, the amount of thermal energy generated per unit time is stabilized, and the accuracy of controlling the thermal energy supply amount is improved. In addition, since excessive heat generation occurs due to the repeated absorption and desorption of hydrogen gas by the phase transition of the hydride alloy, the heat and hydrogen of the PTC heater 140 can be efficiently utilized, and the efficiency can be further enhanced.

[0097] In addition, the heat generating system 100 according to the first embodiment includes a thermal energy generating unit 110 including the heat generating structure 120 and the housing portion 111 that houses the heat generating structure 120, a heater power supply unit 150 that applies a voltage to the PTC heater 140 (an example of a self-controlled heating element) included in the heat generating structure 120, a hydrogen supply unit 160 that supplies hydrogen to the heat generating material 130 included in the heat generating structure 120, and an air supply / discharge amount control unit 170 that controls the air supply / discharge amount from the hydrogen supply unit 160 to the heat generating structure 120.

[0098] According to this configuration, the temperature inside the thermal energy generating unit 110 can be suppressed to be equal to or lower than the upper limit value (temperature T2) of the appropriate heat generation temperature range H1. As a result, the temperature rise of the thermal energy generating unit 110 can be appropriately suppressed without depending on a temperature sensor or heater control, and the safety of the heat generating system 100 can be further enhanced. That is, while enhancing the safety of the system, the temperature of the thermal energy generating unit 110 can be appropriately controlled.

[0099] [Second Embodiment] In the first embodiment, an example of heating a heat generating material using a PTC heater was shown. Thus, when heating a heat generating material using a PTC heater, due to differences in the output of the PTC heater, there may be a difference in the time until the temperature of the PTC heater reaches the appropriate heat generation temperature range H1. For example, when using a PTC heater with a low output, it is possible to prevent the temperature of the PTC heater from exceeding temperature T2, but it takes time to reach the appropriate heat generation temperature range H1. Therefore, it takes time until a heat generation reaction occurs in the heat generating material, and the mobility of the heat generating structure decreases. On the other hand, if a PTC heater with a high output is used to obtain the mobility of the heat generating structure, the temperature may exceed temperature T2, and there is a risk that the heat generation reaction will not occur in the heat generating material.

[0100] Therefore, in the second embodiment, an example is shown in which a plurality of PTC heaters having different operable upper limit temperatures are used to prevent thermal runaway of the system without reducing mobility.

[0101] [Configuration Example of Heat Generation System] FIG. 5 is a schematic configuration diagram showing a configuration example of the heat generation system 300. The heat generation system 300 is a modification of a part of the heat generation system 100 shown in FIG. 1, and is different from the heat generation system 100 in that two types of PTC heaters (the first PTC heater 320 and the second PTC heater 330) are provided. Hereinafter, the description will focus on the differences from the heat generation system 100 shown in FIG. 1.

[0102] The heat generation system 300 includes a heat generating structure 310. The heat generating structure 310 includes a heat generating material 130, a first PTC heater 320, and a second PTC heater 330. The first PTC heater 320 and the second PTC heater 330 have different Curie temperatures. Specifically, the Curie temperature of the first PTC heater 320 is set higher than the Curie temperature of the second PTC heater 330. Further, the first PTC heater 320 is intended to maintain the heat generating material 130 within the range of the appropriate heat generation temperature range H1, while the second PTC heater 330 is intended to shorten the time required for the heat generating material 130 to reach the appropriate heat generation temperature range H1.

[0103] [Configuration Example of Heat Generation Structure] FIG. 6 is a cross-sectional view schematically showing a configuration example of the heat generation structure 310. In FIG. 6, an example is shown in which the heat generating material 130 is constituted by sheet-like heat generating materials 131 and 132, and the sheet-like first PTC heater 320 and the second PTC heater 330 are laminated so as to be sandwiched between the heat generating materials 131 and 132. The configuration example shown in FIG. 6 is a modification of a part of the configuration shown in FIG. 2, and is different from the configuration shown in FIG. 2 in that two types of PTC heaters (the first PTC heater 320 and the second PTC heater 330) are provided. Hereinafter, the description will be centered on the points different from the configuration shown in FIG. 2.

[0104] The first PTC heater 320 includes a sheet-like first resistor 321 and electrodes 341 and 342 arranged so as to sandwich the first resistor 321. In the second embodiment, the maximum value of the temperature that the first PTC heater 320 can stably rise to is described as the operable upper limit temperature Tmax1.

[0105] The second PTC heater 330 includes a sheet-like second resistor 331 and electrodes 341 and 342 arranged so as to sandwich the second resistor 331. In the second embodiment, the maximum value of the temperature that the second PTC heater 330 can stably rise to is described as the operable upper limit temperature Tmax2.

[0106] Since the electrodes 341 and 342 constituting the first PTC heater 320 and the second PTC heater 330 are common, the same voltage is applied to the first resistor 321 and the second resistor 331.

[0107] [Example of Temperature Transition of Heat Generation Structure] FIG. 7 is a diagram showing an example of the temperature transition of the heat generation structure 310. In the graph shown in FIG. 7, the horizontal axis represents the time axis, and the vertical axis represents the temperature. Since the temperature T1, the temperature T2, and the heat generation appropriate temperature region H1 are the same as those shown in FIG. 3, the description thereof is omitted here.

[0108] The temperature Tmax1 indicates the operable upper limit temperature of the first PTC heater 320. The temperature Tmax2 indicates the operable upper limit temperature of the second PTC heater 330. The temperature T3 indicates the room temperature (e.g., about 25°C).

[0109] In the second embodiment, as a PTC heater for the purpose of maintaining the heating material 130 within the range of the proper heating temperature region H1, a first PTC heater 320 is used in which the operable upper limit temperature Tmax1 is within the range of the proper heating temperature region H1. Also, as a PTC heater for the purpose of shortening the time to reach the proper heating temperature region H1 of the heating material 130, a second PTC heater 330 is used in which the operable upper limit temperature Tmax2 is outside the range of the proper heating temperature region H1. That is, the second PTC heater 330 is used only for the purpose of being a temperature lower than the temperature at which the heating material 130 generates excessive heat and for heating up the minimum system. For this reason, the operable upper limit temperature Tmax2 is set outside the range of the proper heating temperature region H1.

[0110] Also, since the second PTC heater 330 is for the purpose of shortening the time to reach the proper heating temperature region H1 of the heating material 130, it is preferable to use a PTC heater in which the temperature rising rate from room temperature to the operable upper limit temperature Tmax2 is faster than that of the first PTC heater 320. When using a PTC heater in which the effective range of the operable lower limit temperature and the operable upper limit temperature is set, the second PTC heater 330 having an operable upper limit temperature higher than the operable lower limit temperature of the first PTC heater 320 is used.

[0111] That is, in the second embodiment, the first PTC heater 320 and the second PTC heater 330 for which Tmax1 > Tmax2 holds are used. Specifically, the first PTC heater 320 and the second PTC heater 330 for which T1 > Tmax2 and T1 < Tmax1 < T2 hold are used.

[0112] Further, a first PTC heater 320 for which the heat generation appropriate temperature region H1 > ΔT is satisfied is used so that the temperature of the heat generating structure 310 falls within the heat generation appropriate temperature region H1. More preferably, a heat generating material 130, a first PTC heater 320, and a second PTC heater 330 that satisfy the following conditions (1) to (4) are used. Condition (1) Tmax1 > Tmax2, Condition (2) Tmax > T1, Condition (3) T2 > Tmax1 + ΔT, Condition (4) Tmax1 - Tmax2 ≧ H1 / 2

[0113] More specifically, in order for the heat energy generation unit 110 to continue generating heat at a constant output, it is preferable that the operable upper limit temperature Tmax1 be the median value (or a value slightly higher than the median value) of the heat generation appropriate temperature region H1. Further, as shown by the curve L2 in FIG. 6, in the operating state of the heat energy generation unit 110, the temperature of the excess heat due to the heat generating material 130 is above the operable upper limit temperature Tmax1, that is, it is preferable that the curve L2 vibrates slightly above the operable upper limit temperature Tmax1.

[0114] For example, when using a first PTC heater 320 for which the operable upper limit temperature Tmax1 is the center of the heat generation appropriate temperature region H1, the difference value H3 between the operable upper limit temperatures Tmax1 and Tmax2 is half or more of the heat generation appropriate temperature region H1. That is, H3 ≧ H1 / 2. In this way, by using a second PTC heater 330 with an operable upper limit temperature Tmax2 such that the difference value H3 between the operable upper limit temperatures Tmax1 and Tmax2 is H1 / 2 or more, heat generation that does not reduce mobility and does not exceed the heat generation appropriate temperature region H1 becomes possible.

[0115] [Examples of the arrangement patterns of the first PTC heater and the second PTC heater] FIGS. 8(a) to (e) are diagrams showing configuration examples of the arrangement patterns of the first PTC heater and the second PTC heater of the heat generating structures 400, 410, 420, 430, and 440. In FIGS. 8(a) to (e), top views of the heat generating structures 400, 410, 420, 430, and 440 are simply attached.

[0116] In FIGS. 8(a) to (e), the rectangles or circles indicating the first resistors 401, 411, 421, 431, 441 constituting the first PTC heater are shaded in gray, and the rectangles or circles indicating the second resistors 402, 412, 422, 432, 442 constituting the second PTC heater are shaded in white. Also, the electrodes 405, 415, 425, 435, 445 constituting the first PTC heater and the second PTC heater are shown as rectangles. Note that the same voltage is applied to each resistor constituting the first PTC heater and the second PTC heater.

[0117] Also, in FIGS. 8(a) to (e), for ease of explanation, an example is shown in which other portions (for example, the gap between the first PTC heater and the second PTC heater) other than the portions where the first PTC heater and the second PTC heater are arranged are made relatively wide. However, for other portions other than the portions where the first PTC heater and the second PTC heater are arranged, it is preferable to make them as narrow as possible in order to improve the heating efficiency by the PTC heater.

[0118] FIGS. 8(a) and 8(c) show examples in which the rectangular resistors 401, 402, 421, 422 are arranged in a grid pattern. However, FIG. 8(a) shows an example in which the first resistors 401 of the first PTC heater are arranged in a row in a specific direction (the left-right direction in FIG. 8(a)), and the second resistors 402 of the second PTC heater are arranged in a row in a specific direction. Also, FIG. 8(a) shows an example in which the first resistors 401 of the first PTC heater and the second resistors 402 of the second PTC heater are alternately arranged and arranged in the orthogonal direction (the up-down direction in FIG. 8(a)). Also, FIG. 8(c) shows an example in which the first resistors 421 of the first PTC heater and the second resistors 422 of the second PTC heater are alternately arranged and arranged in a specific direction (the left-right direction in FIG. 8(c)) and its orthogonal direction (the up-down direction in FIG. 8(c)).

[0119] FIG. 8(b) shows an example in which the rectangular resistors 411, 412 are alternately arranged and arranged in a specific direction (the left-right direction in FIG. 8(b)).

[0120] FIG. 8(d) shows an example in which the rectangular resistors 431 and 432 are arranged obliquely. That is, it shows an example in which a plurality of first resistors 431 arranged in a V shape and a plurality of second resistors 432 arranged in a V shape are alternately arranged in a specific direction (the vertical direction in FIG. 8(d)).

[0121] FIG. 8(e) shows an example in which the elliptical resistors 441 and 442 are arranged so as to spread in the radial direction.

[0122] The arrangement patterns of the first PTC heater and the second PTC heater shown in FIGS. 8(a) to (e) are examples and are not limited thereto, and other arrangements may be used.

[0123] Here, when heat is required for warm-up and heat retention of the internal combustion engine of a hybrid vehicle, a battery heater of an electric vehicle, etc., it is required to quickly supply the required heat energy. That is, when the heat generation system 300 is mounted on a vehicle, it is important to quickly supply the required heat energy. Therefore, in the second embodiment, a heat generation system 300 that uses two types of PTC heaters (the first PTC heater 320 and the second PTC heater 330) to enhance mobility and can quickly supply the required heat energy is used.

[0124] In the second embodiment, an example in which a first PTC heater and a second PTC heater having two different Curie temperatures are used is shown. However, a plurality of types of PTC heaters having three or more different Curie temperatures may be used. In this case, at least two of the plurality of PTC heaters, namely, the PTC heater with the lowest operable upper limit temperature and the highest one, preferably satisfy the conditions of the above-described first PTC heater 320 and second PTC heater 330. Also, for the PTC heater with the lowest operable upper limit temperature, it is preferable to adopt the one with the fastest temperature rise rate, and to make the temperature rise rate of the PTC heater gradually slow down as the operable upper limit temperature increases.

[0125] [Examples and Comparative Examples] Next, examples and comparative examples of the heat generating structure in the second embodiment will be described. Note that the configuration of the heat generating structure 200 in the fourth example and the third comparative example is the same as that in FIG. 4. Also, the method for measuring the total heat generation energy is the same as the measurement method used in the first to third examples and the first and second comparative examples.

[0126] <Fourth Example> In the fourth embodiment, an example is shown in which the difference between Tmax1 and Tmax2 is set to be half or more of the heat generation appropriate temperature range H1. That is, an example is shown in which the difference between Tmax1 and Tmax2 (605 °C = 675 °C - 70 °C) is half (460 °C) or more of the heat generation appropriate temperature range H1 (80 °C to 1000 °C). In other words, an example is shown in which Tmax1 and Tmax2 are significantly separated. That is, an example that satisfies condition (4) is shown.

[0127] [Configuration of Heat Generating Structure] Heat generating material: Pellets made by solidifying zirconium (Zr)-nickel (Ni) powder, First resistor: Bi4Ti3O9, Second resistor: (Ba 0.7 Sr 0.3 )TiO3 [Implementation Conditions] Tmax1 is around 675 °C, Tmax2 is around 70 °C, weight of the heat generating material: 200 g, specific heat of the heat generating material: 0.37 J / (g·°C), T1 = 80 °C, T2 = 1000 °C [Measurement Results] Heat generation amount: 15 W

[0128] In the fourth example, since the difference between Tmax1 and Tmax2 is set to be half or more of the heat generation appropriate temperature range H1, the time until the temperature of the heat generating structure 200 reaches the heat generation appropriate temperature range H1 can be shortened. Thereby, the mobility of the system can be enhanced. Also, appropriate heat generation that does not exceed the appropriate temperature range can be generated.

[0129] <Third Comparative Example> As a comparative example of the fourth embodiment, an example is shown in which the difference between Tmax1 and Tmax2 is set to less than half of the appropriate heat generation temperature range H1. That is, an example is shown in which Tmax1 is lowered and the difference between Tmax1 and Tmax2 (230 °C = 300 °C - 70 °C) is less than half (460 °C) of the appropriate heat generation temperature range H1 (80 °C to 1000 °C). That is, an example that does not satisfy condition (4) is shown.

[0130] [Configuration of the heat generating structure] Heat generating material: Pellets made by solidifying zirconium (Zr)-nickel (Ni) powder, First resistor: (Ba 0.996 Y 0.004 )TiO3, Second resistor: (Ba 0.7 Sr 0.3 )TiO3 [Implementation conditions] Tmax1 is around 300 °C, Tmax2 is around 70 °C, weight of the heat generating material: 200 g, specific heat of the heat generating material: 0.37 J / (g·°C), T1 = 80 °C, T2 = 1000 °C [Measurement results] Heat generation amount: 6.8 W

[0131] In the third comparative example, although heat energy could be generated, since the temperature of Tmax1 was low, the generated heat energy became small. Therefore, the superiority became lower compared to the structure using one PTC heater having Tmax1.

[0132] [Configuration and effects of the second embodiment] The heating structure 310 according to the second embodiment is composed of a plurality of PTC heaters including a first PTC heater 320 (an example of a first self-controlled heating element) and a second PTC heater 330 (an example of a second self-controlled heating element). The second PTC heater 330 includes a second resistor 331 having a Curie temperature different from that of the first resistor 321 included in the first PTC heater 320. The operable upper limit temperature Tmax2 of the second PTC heater 330 is set lower than the first temperature T1. The operable upper limit temperature Tmax1 of the first PTC heater 320 is set within the range of the first temperature T1 and the second temperature T2 (heating appropriate temperature region H1), and is set so that the temperature increase range of the heating material 130 due to excessive heat from the operable upper limit temperature Tmax1 does not exceed the second temperature T2.

[0133] According to this configuration, the time until the temperature of the heating structure 310 reaches (or returns to) the heating appropriate temperature region H1 can be shortened. Thereby, the mobility of the system can be enhanced. In addition, a structure for reducing the temperature fluctuation of the heating structure 310 can be realized.

[0134] In the heating structure 310 according to the second embodiment, the operable upper limit temperature Tmax1 of the first PTC heater 320 is set at the center of the range of the first temperature T1 and the second temperature T2 (heating appropriate temperature region H1). Further, the difference between the operable upper limit temperature Tmax1 of the first PTC heater 320 and the operable upper limit temperature Tmax2 of the second PTC heater 330 is set to be half or more of the range of the first temperature T1 and the second temperature T2 (heating appropriate temperature region H1). Here, the center shown here includes not only the center in a strict sense but also the center and its vicinity.

[0135] According to this configuration, the time until the temperature of the heating structure 310 reaches the heating appropriate temperature region H1 can be shortened, and the mobility of the system can be enhanced.

[0136] The heat-generating structure 310 according to the second embodiment is arranged such that a plurality of first PTC heaters 320 and a plurality of second PTC heaters 330 are adjacent to each other in a plane parallel to the surface of the heat-generating material 130, with each of the plurality of first PTC heaters 320 and the plurality of second PTC heaters 330 in contact with the surface of the heat-generating material 130. For example, as shown in FIGS. 8(a) to (e), the plurality of first PTC heaters and the plurality of second PTC heaters are arranged.

[0137] According to this configuration, by alternately arranging the first resistor 321 of the first PTC heater 320 and the second resistor 331 of the second PTC heater 330, the heat generation efficiency of the entire heat-generating structure 310 can be increased, and the mobility of the system can be further enhanced.

[0138] In the heat-generating structure 310 according to the second embodiment, sheet-like electrodes 341 and 342 common to each of the first PTC heater 320 and the second PTC heater 330 are connected, and the first resistor 321 and the second resistor 331 are arranged adjacent to each other in a plane parallel to the surfaces of the electrodes 341 and 342.

[0139] According to this configuration, by alternately arranging the first resistor 321 and the second resistor 331, the heat generation efficiency of the entire heat-generating structure 310 can be increased, and the mobility of the system can be further enhanced.

[0140] [Third Embodiment] When using a PTC heater in a hydrogen atmosphere, there is a risk that hydrogen will penetrate into the PTC heater and the resistor of the PTC heater will deteriorate. Therefore, in the third embodiment, an example is shown in which a hydrogen permeation prevention material for preventing the penetration of hydrogen into the PTC heater is used to prevent the deterioration of the resistor of the PTC heater due to the penetration of hydrogen into the PTC heater.

[0141] [Configuration Example of Heat-Generating Structure] FIG. 9 is a cross-sectional view showing a configuration example of the heat generating structure 500 in the third embodiment. The heat generating structure 500 shown in FIG. 9 is a modification of a part of the heat generating structure 120 shown in FIG. 2, and is different in that a hydrogen permeation prevention material 510 is added to the PTC heater 140. Here, the same reference numerals are given to the parts common to the heat generating structure 120 shown in FIG. 2, and the description thereof is omitted.

[0142] As shown in FIG. 9, among the PTC heater 140, parts other than the electrodes 142 and 143 connected to the power supply are covered with the hydrogen permeation prevention material 510 to prevent hydrogen from entering the PTC heater 140. In this way, by covering the PTC heater 140 with the hydrogen permeation prevention material 510, deterioration of the resistor 141 of the PTC heater 140 in a hydrogen atmosphere can be prevented. Thereby, the self-controlled heat generation of the PTC heater 140 can be maintained over a long period of time. Note that, as the hydrogen permeation prevention material 510, for example, polyimide or Si3N4 (silicon nitride) can be used.

[0143] Note that the third embodiment is also applicable to the plurality of PTC heaters (the plurality of PTC heaters each including a resistor having a different Curie temperature) shown in the second embodiment. For example, in the example shown in FIG. 6, among the first PTC heater 320 and the second PTC heater 330, parts other than the electrodes 341 and 342 connected to the power supply are covered with the hydrogen permeation prevention material 510 to prevent hydrogen from entering the first PTC heater 320 and the second PTC heater 330. In this way, by covering the first PTC heater 320 and the second PTC heater 330 with the hydrogen permeation prevention material 510, deterioration of the first resistor 321 of the first PTC heater 320 and the second resistor 331 of the second PTC heater 330 in a hydrogen atmosphere can be prevented.

[0144] [Configuration and Effect of the Third Embodiment] The heat generating structure 500 according to the third embodiment is configured to cover the periphery of the PTC heater 140 (an example of a self-controlled heat generating body) with the hydrogen permeation prevention material 510.

[0145] According to this configuration, by covering the periphery of the PTC heater 140 with the hydrogen permeation prevention material 510, deterioration of the PTC material in a hydrogen atmosphere can be prevented. Further, the self-controlled heat generation function of the PTC heater 140 can be maintained over a long period of time, and a structure enabling stable operation over a long period of time can be realized.

[0146] As described above, the embodiments of the present invention have been described. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Explanation of Reference Numerals

[0147] 100, 300 Heating system, 110 Heat energy generation unit, 111 Accommodation unit, 120, 310, 500 Heating structure, 130 to 132 Heating materials, 140 PTC heater, 141 Resistor, 142, 143, 341, 342 Electrodes, 150 Heater power supply unit, 160 Hydrogen supply unit, 170 Supply and exhaust air volume control unit, 180 Control unit, 191 to 193 Target components 320 First PTC heater, 330 Second PTC heater, 321 First resistor, 331 Second resistor, 510 Hydrogen permeation prevention material

Claims

1. A heat generating structure comprising a heat generating material containing a hydrogen storage material and a self - controlled heating element that supplies heat to the heat generating material, wherein the self - controlled heating element includes a resistor whose electrical resistance rapidly increases when the Curie temperature is reached and an electrode connected to the resistor, the operable upper limit temperature of the self - controlled heating element is set within the range between a first temperature at which the hydrogen storage material starts to desorb hydrogen and a second temperature at which the crystal structure of the hydrogen storage material starts to change, and the temperature rise value due to excessive heat of the heat generating material from the operable upper limit temperature is set not to exceed the second temperature. A heat generating structure.

2. The heat generating structure according to Claim 1, wherein the self - controlled heating element is composed of a plurality of self - controlled heating elements including a first self - controlled heating element and a second self - controlled heating element, the second self - controlled heating element includes a second resistor having a Curie temperature different from that of a first resistor included in the first self - controlled heating element, the operable upper limit temperature of the second self - controlled heating element is set lower than the first temperature, the operable upper limit temperature of the first self - controlled heating element is set within the range of the first temperature and the second temperature, and the temperature rise width due to excessive heat of the heat generating material from the operable upper limit temperature is set not to exceed the second temperature. A heat generating structure.

3. The heat generating structure according to Claim 2, wherein the operable upper limit temperature of the first self - controlled heating element is set at the center of the range of the first temperature and the second temperature, the difference between the operable upper limit temperature of the first self - controlled heating element and the operable upper limit temperature of the second self - controlled heating element is set to be equal to or more than half of the range of the first temperature and the second temperature. A heat generating structure.

4. The heat generating structure according to Claim 2 or 3, wherein the first self - controlled heating element and the second self - controlled heating element are arranged adjacent to each other in a plane parallel to the surface of the heat generating material such that each of the plurality of first self - controlled heating elements and each of the plurality of second self - controlled heating elements are in contact with the surface of the heat generating material. A heat generating structure.

5. The heat generating structure according to Claim 4, a common sheet - like electrode is connected to each of the first self - controlled heating element and the second self - controlled heating element, the first resistor and the second resistor are arranged adjacent to each other in a plane parallel to the surface of the electrode. A heat generating structure.

6. The exothermic structure according to any one of claims 1 to 5, characterized in that the periphery of the self-controlled heating element is covered with a hydrogen permeation prevention material. Exothermic structure.

7. The exothermic structure according to any one of claims 1 to 6, wherein when the exothermic structure is in an operating state, the temperature of the gas phase part of the accommodating part for accommodating the exothermic structure is set as the operating reference temperature, and the pressure of the gas phase part is set as the operating reference pressure. Exothermic structure.

8. A heat energy generation unit including the exothermic structure according to any one of claims 1 to 7 and an accommodating part for accommodating the exothermic structure, a heating element control unit for controlling the application of voltage to the self-controlled heating element included in the exothermic structure, a hydrogen supply unit for supplying hydrogen to the heating material included in the exothermic structure, and an air supply and exhaust amount control unit for controlling the air supply and exhaust amount from the hydrogen supply unit to the exothermic structure. Exothermic system.

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