JP2021099054A - Power generator, charger, power generation method, charging method, power charging/generating system, and heat engine - Google Patents

Abstract

To provide a power generator etc. which enables improvement of energy recovery efficiency.SOLUTION: A power generator includes: a power charging/generating machine 10 which generates power with expansion energy generated when liquid air K21 turns to a gas from a liquid; a heat exchanger 30 which heats the liquid air K21 before the liquid air K21 flows into the power charging/generating machine 10 to change a phase of the liquid air K21 from the liquid to the gas and cools air K24 after the air K24 is discharged from the power charging/generating machine 10 to conduct heat exchange between the liquid air K21 and the air K24; and a heat exchanger 40 which conducts heat exchange with air K25 discharged from the heat exchanger 30 to cool the air K25 further and return at least part of the air K25 from the gas to the liquid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power generation device, a charging device, a power generation method, a charging method, a charging power generation system, and a heat engine.

Conventionally, in order to level the electric power and improve the operating rate of the equipment for photovoltaic power generation, for example, the surplus electric power generated in the photovoltaic power generation is stored during the daytime on weekends, and the electric power in the morning and evening on weekdays. There is a power storage system that generates electricity when it is tight. As such an electric power storage system, there is a system that uses a fluid such as air as a heat medium, compresses and cools a fluid in a gaseous state to make a liquid, and stores electric power as cold heat.

Patent Document 1 describes a cryogenic power generation system. In this cryogenic power generation system, in the "air liquefaction process", when there is surplus electric power, the compressor of the air liquefier is driven by using the surplus electric power, and the raw material air is compressed. This air is cooled by the cooler, the air is cooled by the low temperature air from the receiving tank by the heat exchanger, and then the temperature is lowered by adiabatic expansion by the expansion valve to become liquid air, which is stored in the receiving tank. In the "liquid air storage process", liquid air is stored in a storage tank. In the "liquid air vaporization step", the liquid air in the storage tank is heated by the vaporizer to become high pressure. In the "power generation device drive process", high-pressure air from the carburetor is injected into steam to increase the output of the turbine, and the amount of power generated by the generator increases by the amount of the increased output.
Further, in Patent Document 2, liquid air injected into the liquefied layer of a cold insulation tank is sprayed at high pressure on an electric heater with a high-pressure pump to heat and expand it to drive a turbine for power generation and a generator, and then a heat exchanger. The vaporized air discharged from the power generation turbine is introduced into the air, and the vaporized air is sent to the vaporization layer of the cold insulation tank by the exhaust pressure of the power generation turbine, and most of the vaporized air is released to the atmosphere from the pressure regulating valve, and the rest. The vaporized air is regenerated into liquid air by a refrigerating liquefier, and the liquid air injected into the cold storage tank is pumped to the heat exchange tube by a high-pressure pump, and the vaporized air discharged from the power generation turbine is pumped to the expansion valve. A power generation device that regenerates liquid air with an expansion valve and sends it to a cold storage tank is described.

Japanese Unexamined Patent Publication No. 9-191586 Japanese Unexamined Patent Publication No. 2012-17725

However, in an electric power storage system that uses a fluid such as air as such a heat medium, it is necessary to apply a large amount of heat in order to return the fluid from a liquid to a gas state during power generation. In addition, a large amount of cold heat still remains in the air after power generation, but in the current system, this is released to the outside air as it is. If the heat given and the heat released can be effectively used, the energy recovery efficiency can be improved.
An object of the present invention is, for example, to improve the energy recovery efficiency in a power generation device or a charging power generation system.

Thus, according to the present invention, the power generation means that generates power by the expansion energy when the fluid changes from liquid to gas and the fluid before flowing into the power generation means are heated to change the phase of the fluid from liquid to gas. The fluid is further cooled by cooling the fluid discharged from the power generation means and exchanging heat with the first heat exchange means for exchanging heat between them and the fluid discharged from the first heat exchange means. A power generator is provided that comprises a second heat exchange means that returns at least a portion of the fluid from a gas to a liquid state. In this case, the fluid can be reliquefied by the first heat exchange means and the second heat exchange means, and the energy recovery efficiency can be improved.

Here, an expansion means for returning the fluid to a liquid state by expanding the fluid discharged from the second heat exchange means is further provided, and the second heat exchange means remains without becoming a liquid by the expansion means. It is possible to exchange heat with a fluid in a gaseous state. In this case, liquefaction of the fluid can be promoted.
Further, the fluid discharged from the power generation means can be further cooled by exchanging heat with the fluid in a gaseous state that does not become a liquid but remains as a liquid by the expansion means. In this case, the cold heat of the fluid in the gaseous state can be recovered.
Further, the fluid before flowing into the power generation means can be heated by external heat other than the heat generated by the own device in addition to the first heat exchange means. In this case, more expansion energy can be given to the fluid.
Further, a heat storage means for storing heat is further provided, and the fluid before flowing into the power generation means can be heated by the heat stored in the heat storage means in addition to the first heat exchange means. In this case, the heat generated during charging can be utilized.
Further, the gas that does not become liquid by the expansion means and remains after exchanging heat with the fluid after being discharged from the power generation means can be sent to an external device that utilizes the cold heat of the fluid. In this case, the cold heat can be used more efficiently by the external device.

Further, according to the present invention, a compression means that compresses a fluid in a gaseous state by using electric power and stores compression energy in the fluid and a heat exchange that cools the fluid compressed by the compression means by performing heat exchange. The means, the expansion means that expands the fluid discharged from the heat exchange means to change at least a part of the fluid from the gas to the liquid state, and the expansion means that the expansion means compresses the fluid in the residual gaseous state without becoming liquid. A charging device is provided that comprises a mixing means that mixes with the fluid before it flows into the means. In this case, the cold heat of the fluid in the state of the remaining gas can be used to cool the fluid before it flows into the compression means, and the energy recovery efficiency can be improved.

Further, according to the present invention, there is a power generation process in which power is generated by the expansion energy when the fluid changes from liquid to gas, and a power generation process in which the fluid is phase-changed from liquid to gas by heating the fluid before the power generation process. A first heat exchange step in which the subsequent fluid is cooled and heat exchange is performed between them, and a heat exchange is performed with the fluid after the first heat exchange step to further cool the fluid and at least one of the fluids. A power generation method comprising a second heat exchange step of returning the part from a gas to a liquid state is provided. In this case, the fluid can be reliquefied by the first heat exchange step and the second heat exchange step, and the energy recovery efficiency can be improved.

Further, according to the present invention, a compression step of compressing a fluid in a gaseous state by using electric power and storing compression energy in the fluid, and a heat of cooling the fluid compressed by the compression step by performing heat exchange. The exchange step, the expansion step of expanding the fluid after the heat exchange step to change at least a part of the fluid from a gas to a liquid state, and the expansion step of compressing the fluid in a gaseous state remaining without becoming a liquid in the expansion step. A charging method comprising a mixing step of mixing with a pre-step fluid is provided. In this case, the cold heat of the fluid in the state of the remaining gas can be used to cool the fluid before it flows into the compression step, and the energy recovery efficiency can be improved.

According to the present invention, there are a power generation operation in which power is generated by the expansion energy when the fluid changes from a liquid to a gas, and a charging operation in which the fluid in a gaseous state is compressed by using the electric power and the compressed energy is stored in the fluid. By heating the fluid before it flows into the operating means when performing the power generation operation and the operating means that switches between, the fluid is phase-changed from liquid to gas, and the fluid after being discharged from the operating means is cooled. Then, the first heat exchange means for exchanging heat between them and the fluid discharged from the first heat exchange means during the power generation operation are further cooled, and at least a part of the fluid is changed from gas to liquid. A rechargeable power generation system comprising a second heat exchange means for returning to the state is provided. In this case, the reciprocating efficiency during charging and power generation can be increased.

Here, an expansion means for returning the fluid to a liquid state by expanding the fluid discharged from the second heat exchange means is further provided, and when the charging operation is performed, the second heat exchange means is provided by the expansion means. The fluid can be cooled by exchanging heat with the fluid in a gaseous state that remains without becoming a liquid. In this case, liquefaction of the fluid can be promoted.
Further, when performing the charging operation, the fluid after being discharged from the operating means is cooled by exchanging heat with the fluid in the state of a gas remaining without becoming a liquid by the expanding means. Can be done. In this case, the cold heat of the fluid in the gaseous state can be recovered.
Further, it is possible to further provide a mixing means for mixing the fluid in a gaseous state that remains without becoming a liquid by the expanding means with the fluid before flowing into the operating means. In this case, the cooling of the fluid can be performed by utilizing the cold heat of the fluid in the state of the remaining gas, and the energy recovery efficiency can be improved.
Further further, a heat storage means for accumulating heat is further provided, and the heat storage means stores the heat generated from the operating means when performing the charging operation, and stores the fluid before flowing into the operating means when performing the power generation operation. , Can be heated by the accumulated heat. In this case, the heat generated during charging can be utilized, and the energy recovery efficiency can be further improved.

Further, according to the present invention, there is a first heat exchange between a work process in which work is performed by utilizing the expansion energy when the fluid changes from a liquid to a gas, and a fluid before the work process and a fluid after the work process. A heating process that heats the fluid before the work process, a first cooling process that cools the fluid after the work process by the first heat exchange, and a second cooling process for the fluid after the first cooling process. A heat engine is provided that uses a thermal cycle with a second cooling process that further cools the fluid by performing heat exchange and returns at least a portion of the fluid from a gas to a liquid state. In this case, the fluid can be reliquefied by the first cooling process and the second cooling process, and the energy recovery efficiency can be improved.

Here, by expanding the fluid discharged from the second cooling process, it is possible to further provide an expansion process for returning the fluid to a liquid state. In this case, liquefaction of the fluid can be promoted.
In addition, a pressurizing process for pressurizing the liquid can be further provided before the work process. In this case, the expansion energy of the fluid increases.

According to the present invention, it is possible to increase the energy recovery efficiency in a power generation device or a charging power generation system.

(A) to (b) are diagrams showing an overall configuration example of the charging power generation system according to the present embodiment. It is a flowchart explaining the operation of the charge power generation system at the time of charging. It is a figure which showed the ph diagram of the charge power generation system at the time of charging. It is a flowchart explaining the operation of the charge power generation system at the time of power generation. It is a figure which showed the ph diagram of the charge power generation system at the time of power generation. It is a figure which showed the ph diagram of the conventional charge power generation system at the time of power generation. (A) is a flowchart showing the control of the charge power generation system at the time of charging. (B) is a flowchart showing the control of the charge power generation system at the time of power generation. (A)-(b) is a figure which showed the 1st modification of the charge power generation system. (A)-(b) is a figure which showed the 2nd modification of the charge power generation system. (A)-(b) is a figure which showed the 3rd modification of the charge power generation system. (A)-(b) is a figure which showed the 4th modification of the charge power generation system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<Conventional form>
As a conventional power storage system, a method using a storage battery or hydrogen is common. The former charges the secondary battery to store electric power. The latter also produces hydrogen by electrolyzing water and stores electric power as hydrogen. In this case, electric power can be taken out by converting electric energy into chemical energy and storing it, and conversely by converting chemical energy into electric energy. However, in this case, special chemical materials are used in each case, and the chemical materials deteriorate after long-term operation. Therefore, the running cost tends to be high because the chemical material needs to be replaced.

To solve this drawback, for example, there is a compressed air storage system. It uses electric power to compress air and store it as compressed air. However, this method requires a large volume of a tank for storing compressed air, and requires a large installation area and installation cost. Therefore, it is not realistic to install it in an area that requires a lot of money, especially for a site such as an urban area.

On the other hand, there is a liquid air storage system that turns air into a liquid and stores electric power as liquid air. Since this liquid air storage system uses liquid air, the volume of the storage tank can be smaller than that of the compressed air storage system, and the installation area and installation cost can be reduced. This liquid air storage system liquefies the air, for example, by compressing the air with a compressor and removing heat during charging to store electricity. Further, at the time of power generation for extracting electric power, air is vaporized by applying heat to liquid air, and the pressure generated at that time is used to rotate a turbine to generate electric power to generate electric power. Since it is necessary to apply heat to the liquid air at the time of power generation, the exhaust heat of the boiler may be used or an electric heater may be used as the heat to be added. In some cases, solar heat is used. That is, an external heat source is required.

There is also a system that burns high-pressure air obtained during power generation by an internal combustion engine or a gas turbine to generate power with high efficiency, but it requires fuel for combustion and is not _{CO 2-free.} In addition, the energy recovery efficiency of the system tends to decrease. In addition, a system that uses a large number of heat exchangers to improve energy recovery efficiency has recently been proposed, but the system as a whole becomes complicated, the cost required for equipment becomes large, and cold heat that cannot be used is used. By releasing the exhaust heat to the outside air, the energy recovery efficiency of the system tends to decrease.
Therefore, in the present embodiment, the above problem is suppressed by the following charging / power generation system 1.
In the following description, the case where air is used as a heat medium will be mainly described, but the description is not limited to air. That is, any fluid that can undergo a phase change between a liquid state and a gas state can be applied not only to air but also as a heat medium. Examples of such a fluid include nitrogen (N ₂ ), oxygen (O ₂ ), carbon dioxide (CO ₂ ), ammonia (NH ₃ ), chlorofluorocarbons, ether and the like.

<Explanation of the overall configuration of the charging power generation system 1>
1A to 1B are diagrams showing an overall configuration example of the charging power generation system 1 according to the present embodiment. Of these, FIG. 1A is a diagram showing the charging power generation system 1 during charging. In this case, the charging power generation system 1 can be regarded as a charging device. Further, FIG. 1B is a diagram showing a charge power generation system 1 at the time of power generation. In this case, the charging power generation system 1 can be regarded as a power generation device.

As shown in the figure, the charge power generation system 1 of the present embodiment includes a charge generator 10 for compressing and generating air, a heat storage device 20 for storing heat, and heat exchangers 30 and 40 for heat exchange. It includes an expansion valve 50 that expands air, a tank 60 that stores liquid air, a mixing valve 70 that mixes air at different temperatures, and a control unit 80 that controls the entire charging power generation system 1. Further, the charging power generation system 1 includes a pump P that sends out liquid air from the tank 60. As described above, the charge power generation system 1 of the present embodiment operates with the same device configuration at the time of charging shown in FIG. 1 (a) and at the time of power generation shown in FIG. 1 (b).

At the time of charging shown in FIG. 1A, the recharger 10 uses electric power to rotate the motor 10a, thereby operating the compressor 10b, so that the air taken in from the outside air and flows into the recharger 10 Compress K11. That is, the motor 10a provided in the recharger 10 is operated by using electric power to compress the air K11. At the time of charging, the recharger 10 functions as a compression means for compressing the air K11 in a gaseous state by using electric power and storing the compression energy in the air K11.

On the other hand, at the time of power generation shown in FIG. 1B, the recharger 10 uses the pressure of the air K23 vaporized by the liquid air K21 to rotate the turbine 10c, thereby operating the generator 10d to generate power. I do. The recharger 10 functions as a power generation means for generating power by the expansion energy when the air K11 changes from a liquid to a gas during power generation.

In the present embodiment, the recharger 10 is a device that performs both air compression and power generation. Therefore, the recharger 10 has a power generation operation in which power is generated by the expansion energy when the air changes from a liquid to a gas, and a charging operation in which the gas state air is compressed by using the electric power and the compressed energy is stored in the air. It can also be considered as an operation means for switching between.
For convenience, the motor 10a and the generator 10d have been described separately, but in the example shown in FIG. 1, both are the same device. The recharger 10 is a uniaxial device in which a compressor 10b, a motor 10a (generator 10d), and a turbine 10c are arranged on one axis. Further, as shown in FIG. 1, it is preferable that the compressor 10b and the turbine 10c are of a multi-stage type. As will be described in detail later, the motor 10a and the generator 10d may be separated and used as separate devices.

The heat storage device 20 is an example of a heat storage means and is a device for storing heat. The heat storage device 20 includes a heat storage material that stores heat.
The heat storage device 20 stores the heat generated from the recharger 10 in the heat storage material at the time of charging shown in FIG. 1 (a). That is, since heat is generated when the air K11 is compressed by the motor 10a, this heat is provided in the heat storage material.
On the other hand, the heat storage device 20 releases heat from the heat storage material to heat the air K22 at the time of power generation shown in FIG. 1 (b). As a result, the vaporized air K22 can be further expanded into the expanded air K23.
The heat storage material is not particularly limited as long as it can store heat, but for example, a sensible heat storage material that utilizes the specific heat of a substance can be used. Examples of sensible heat storage materials include water, oil, concrete, brick and the like. It is also possible to use a latent heat storage material that utilizes the phase transition of a substance or a chemical heat storage material that utilizes heat absorption and heat generation during a chemical reaction. Examples of the latent heat storage material include ice-water, sodium acetate trihydrate (CH ₃ COONa, 3H ₂ O), etc., which utilize a solid-liquid phase transition. Further, examples of the chemical heat storage material include those utilizing an absorption reaction, a mixing reaction, and a hydration reaction.

The heat exchangers 30 and 40 are devices that exchange heat between air having different temperatures.
Of these, the heat exchanger 30 functions as a heat exchange means for cooling the air K12 compressed by the recharger 10 by performing heat exchange during charging shown in FIG. 1 (a). As described above, when the air K11 is compressed by the motor 10a, heat is generated, and the air K12 becomes hotter than before flowing into the recharger 10. Further, from the tank 60 for storing the liquid air K16, air K15 in a gaseous state called boil-off gas is generated, which will be described in detail later. This boil-off gas has a temperature close to the boiling point of air and is extremely low temperature. In the heat exchanger 30, heat is transferred from the compressed air K12 to the boil-off gas air K15 to cool the compressed air K12. As a result, the compressed air K12 becomes the air K13 cooled to an extremely low temperature immediately before liquefaction.

The heat exchanger 30 functions as a first heat exchange means at the time of power generation shown in FIG. 1 (b). The heat exchanger 30 exchanges heat between the liquid air K21 in a liquid state before flowing into the recharger 10 and the gaseous air K24 after discharging from the recharger 10. The gaseous air K24 discharged from the turbine 10c of the recharger 10 has a higher temperature than the liquid air K21 discharged from the tank 60. Therefore, in the heat exchanger 30, the liquid air K21 is heated by transferring heat from the air K24 discharged from the turbine 10c to the liquid air K21 discharged from the tank 60. Then, by this heat exchange, the liquid air K21 before flowing into the recharger 10 can be heated to make the air K22 in which the air is phase-changed from a liquid to a gas. Further, by this heat exchange, the heat exchanger 30 cools the air K24 after being discharged from the recharger generator 10.

Further, at the time of power generation, the air K24 after being discharged from the recharger 10 is further cooled by exchanging heat with the air K27 which is a boil-off gas. That is, the air K24 discharged from the recharger 10 is cooled by both the liquid air K21 discharged from the tank 60 and the air K27 which is the boil-off gas. As a result, the air K24 becomes the air K25 cooled to an extremely low temperature immediately before liquefaction. The air K29 after heat exchange with the heat exchanger 30 is released to the outside air and exhausted. However, the air K29 still has sufficient cold heat, and may be sent to an external device that utilizes the cold heat of the air K29. The external device is, for example, an air conditioner, a cooling device for a refrigerating warehouse, an air separation gas producing device, and the like. Then, by operating these devices by utilizing the cold heat of the air K29, the efficiency of these devices is improved.

The heat exchanger 40 is arranged in the tank 60.
Then, the heat exchanger 40 functions as a heat exchange means similar to the heat exchanger 30 at the time of charging shown in FIG. 1 (a). The air K13 discharged from the heat exchanger 30 exchanges heat with the air K15, which is the boil-off gas in the tank 60, by the heat exchanger 40, and becomes the further cooled air K14. As a result, the air K14 can be cooled to the liquid air temperature.
At the time of power generation shown in FIG. 1B, the heat exchanger 40 further cools the air K25 by exchanging heat with the air K25 discharged from the heat exchanger 30, and at least a part of the air K25 is changed from gas to liquid. It functions as a second heat exchange means for the air K26 returned to the above state. At this time, the heat exchanger 40 exchanges heat with the air K27, which is a boil-off gas, as in the case of power generation.

The expansion valve 50 is arranged in the tank 60. The expansion valve 50 functions as an expansion means for changing at least a part of the air from a gas to a liquid by expanding the air K14 discharged from the heat exchanger 40 during charging shown in FIG. 1 (a). As described above, the heat exchanger 40 cools the air K14 to the liquid air temperature. Then, when it is rapidly expanded by the expansion valve 50, at least a part of it is liquefied by the Joule-Thomson effect to become liquid air K16. Since the expansion valve 50 is arranged in the tank 60, the liquid air K16 is stored in the lower part of the tank 60. Further, the air K15 in a gaseous state that does not become liquid but remains due to the expansion valve 50 is called boil-off gas and accumulates in the upper part of the tank 60. Then, when the air K15, which is the boil-off gas, exceeds a predetermined pressure, the check valve 60a opens. Then, the air K15 is discharged toward the heat exchanger 30.
The expansion valve 50 functions as an expansion means for returning the air K26 to a liquid state by expanding the air K26 discharged from the heat exchanger 40 during power generation shown in FIG. 1 (b). This action is the same as during charging, and when it is rapidly expanded by the expansion valve 50, at least a part of it is liquefied by the Joule-Thomson effect to become liquid air K28. Further, the air K27 in the state of a gas remaining without becoming a liquid by the expansion valve 50 is a boil-off gas.

The tank 60 stores liquid air K16, K28, and air K15, K27. Since these are extremely low temperatures, the tank 60 needs to be made of a material that is resistant to this temperature and is less likely to cause low temperature brittleness, and also has excellent heat insulating properties. Therefore, for example, the tank 60 has a dewar bottle structure in which the outer wall is a stainless steel double wall and the space between the double walls is a high vacuum. Further, for example, the structure may be such that it is kept cold by a heat insulating material.

The mixing valve 70 is used during charging as shown in FIG. 1 (a). The mixing valve 70 functions as a mixing means for mixing the air K17, which is the boil-off gas after passing through the heat exchanger 30, with the air K11 before flowing into the recharger 10. That is, in the present embodiment, the boil-off gas is not released to the outside air and is used for cooling the air K11. Thereby, the energy recovery efficiency of the charge power generation system 1 can be improved. Further, the impurities contained in the air K11 are condensed by being cooled. Thereby, impurities contained in the air K11 can be removed. This impurity is, for example, water or carbon dioxide.

At the time of charging shown in FIG. 1A, the control unit 80 controls for producing the liquid air K16 by using electric power. On the other hand, at the time of power generation shown in FIG. 1B, the control unit 80 returns the liquid air K16 to a gaseous state, and controls to generate electric power by the generator 10d by utilizing the expansion energy when it becomes gas. .. The specific control performed by the control unit 80 will be described later.

<Explanation of operation of charge power generation system 1>
Next, the operation of the charge power generation system 1 shown in FIG. 1 will be described.
(Operation during charging)
First, the operation when charging electric power by using the charging power generation system 1 will be described.
FIG. 2 is a flowchart illustrating the operation of the charging power generation system 1 during charging. Further, FIG. 3 is a diagram showing a ph diagram of the charging power generation system 1 during charging. In FIG. 3, the horizontal axis represents the specific enthalpy (h) and the vertical axis represents the pressure (p).

At the time of charging, first, the motor 10a of the recharger 10 is operated by electric power, and air K11 is taken in from the outside air (step 101). The pressure of the air K11 at this time is atmospheric pressure p0. The temperature of the air K11 is room temperature, for example, 25 ° C.

Next, the air K11 and the air K17, which is a boil-off gas, are mixed by the mixing valve 70 (step 102). As a result, the air K11 is cooled and impurities contained in the air K11 are removed. With reference to the ph diagram at this time, the pressure (p) is the atmospheric pressure p0 and does not change, but the specific enthalpy (h) decreases as the temperature decreases due to the mixing of air K17.

Further, the air K11 is compressed by the compressor-10b of the recharger 10 (step 103). With reference to the ph diagram at this time, the pressure (p) and the specific enthalpy (h) are both increased by compression.

Then, at this time, the heat generated from the recharger 10 is stored in the heat storage material of the heat storage device 20 (step 104). With reference to the ph diagram at this time, the pressure (p) does not change, but the specific enthalpy (h) decreases as heat is removed from the air K11 and the temperature decreases.

The compression and heat removal of the air K11 shown in steps 103 and 104 may be repeated a predetermined number of times. In this case, if steps 103 and 104 are repeated a predetermined number of times (Yes in step 105), the process proceeds to step 106. On the other hand, if it has not been repeated a predetermined number of times (No in step 105), the process returns to step 103.
The ph diagram of FIG. 3 shows an example in which step 103 and step 104 are repeated twice by the recharger generator 10. As a result, the pressure (p) reaches the maximum pressure ph1.

Next, the compressed air K11 is expanded to an intermediate pressure pm1, and the turbine 10c is rotated by this expansion energy (step 106). As described above, since the recharger 10 is a uniaxial device in which the compressor 10b, the motor 10a (generator 10d), and the turbine 10c are arranged on one axis, the rotational force generated by the turbine 10c is the compressor 10b. It is used as a power to operate. Step 106 is a step of adiabatically expanding the compressed air K11 to an intermediate pressure pm1. By this step, the air K11 can be cooled to just before liquefaction. With reference to the ph diagram at this time, both the pressure (p) and the specific enthalpy (h) decrease due to adiabatic expansion.

Then, the air K12 discharged from the recharger 10 flows into the heat exchanger 30 and performs the first heat exchange with the air K15 which is the boil-off gas (step 107). As a result, the air K12 is further cooled to become the air K13. With reference to the ph diagram at this time, the pressure (p) does not change at the intermediate pressure pm1, but the specific enthalpy (h) decreases as the air K12 is cooled.

Further, the air K13 discharged from the heat exchanger 30 flows into the heat exchanger 40 and performs a second heat exchange with the air K15 which is a boil-off gas (step 108). As a result, the air K13 is further cooled to become the air K14. With reference to the ph diagram at this time, the pressure (p) does not change at the intermediate pressure pm1, but the specific enthalpy (h) decreases as the air K13 is cooled. Further, it can be seen that the air K14 is cooled to the liquid air temperature and is in a mixed state of gas and liquid (gas-liquid mixing).

Next, the air K14 is expanded inside the tank 60 by the expansion valve 50 (step 109). At this time, the temperature of the air K14 drops due to the Joule-Thomson effect. The liquid air K16 that has become liquid is stored in the tank 60. The pressure in the tank 60 at this time is, for example, atmospheric pressure p0. The temperature of the liquid air K16 is, for example, -196 ° C. With reference to the ph diagram at this time, the pressure (p) decreases, but the specific enthalpy (h) is a conserved Joule-Thomson expansion.
By the above series of steps, the intake air K11 can be liquefied into liquid air K16. Further, the series of steps can be considered as a step of charging electric power in the form of liquid air K16.
Further, the air K15 in a gaseous state without becoming a liquid is used as a boil-off gas with the heat exchanges in the heat exchangers 30 and 40 in steps 107 and 108 described above, and with the air K11 in the mixing valve 70 in step 102. It is used for mixing.

When the charging power generation system 1 is started, it is preferable to operate the pump P to send the liquid air K16 from the tank 60 as the liquid air K18. As a result, the heat exchanger 30 is cooled to the operating temperature, and the air K12 discharged from the recharger 10 is cooled. Further, in the heat exchanger 30, the liquid air K18 is heated to become the gaseous air K19, which is mixed with the boil-off gas air K17 and further mixed with the intake air K11.

The above-mentioned step 103 can be regarded as a compression step of compressing air in a gaseous state by using electric power and storing compression energy in the air.
Further, step 107 can be regarded as a heat exchange step of cooling the air K12 compressed by the compression step by performing heat exchange.
Further, step 109 can be regarded as an expansion step in which at least a part of the air is changed from a gas to a liquid by expanding the air K14 after the heat exchange step.
Then, the step 102 can be regarded as a mixing step of mixing the air K17 in a gaseous state that remains without becoming a liquid in the expansion step of the step 109 with the air before the compression step of the step 103.
Further, the charging operation of the charging power generation system 1 described above can be considered as a charging method including the compression step, the heat exchange step, the expansion stroke, and the mixing step described above.

The air K11 is preferably further cooled with cooling water or the like. This corresponds to the point T11 moving in the direction of the arrow Y11 in the ph diagram of FIG. Further, it is more preferable that the maximum pressure ph1 is large. This corresponds to the movement of the maximum pressure ph1 in the direction of arrow Y12 in the ph diagram of FIG. Further, the pressure in the tank 60 was atmospheric pressure p0 in the above-mentioned example, but by increasing this pressure, the liquefaction rate of air can be further increased. This corresponds to the point T13 moving in the direction of the arrow Y13 in the ph diagram of FIG. By doing so, the energy recovery efficiency of the rechargeable power generation system 1 is further improved.
Further, in the ph diagram of FIG. 3, the intermediate pressure pm1 and the maximum pressure ph1 are set smaller than the saturation pressure pc. That is, pc> pm1 and pc> ph1. However, the present invention is not limited to this, and the intermediate pressure pm1 and the maximum pressure ph1 may be set larger than the saturation pressure pc. That is, pc <pm1 and pc <ph1 may be set.

(Operation during power generation)
Next, the operation when generating power using the charge power generation system 1 will be described.
FIG. 4 is a flowchart illustrating the operation of the charge power generation system 1 during power generation. Further, FIG. 5 is a diagram showing a ph diagram of the charge power generation system 1 at the time of power generation.

At the time of power generation, first, the pump P is used to send the liquid air K28 from the tank 60 as the liquid air K21 (step 201). At this time, the liquid air K21 is boosted by the pump P. With reference to the ph diagram at this time, the pressure (p) reaches the maximum pressure ph2 by being boosted by the pump P.

Next, the liquid air K21 flows into the heat exchanger 30 and exchanges heat with the air K24 discharged from the recharger 10 (step 202). As a result, the liquid air K21 is heated to become the air K22. With reference to the ph diagram at this time, the pressure (p) does not change, but the specific enthalpy (h) increases with heating. Further, at this time, it can be seen that the air K22 is in a mixed state of gas and liquid. However, the present invention is not limited to this, and the air K22 after step 202 may be in a gas-only state or a liquid-only state.

Then, the air K22 is further heated by the heat accumulated in the heat storage device 20 (step 203). As a result, the liquid air K21 is heated to become the gaseous air K23. With reference to the ph diagram at this time, the pressure (p) does not change, but the specific enthalpy (h) is further increased by heating. Further, at this time, it can be seen that the air K23 is in a gaseous state. The air K23 has the maximum specific enthalpy (h), and the temperature at this time is, for example, 25 ° C. at room temperature.

In steps 202 and 203, the air K22 and the air K23 may be further heated by external heat other than the heat generated by the own device. The external heat is not particularly limited, but specifically, the heat supplied from the atmosphere at room temperature is used. Moreover, you may use water at room temperature. A heat exchanger for supplying external heat may be further installed.

Next, the air K23 flows into the recharger 10 and uses its expansion energy to rotate the turbine 10c, thereby operating the generator 10d to generate electricity. (Step 204). Step 204 is a step of adiabatically expanding the air K23. With reference to the ph diagram at this time, both the pressure (p) and the specific enthalpy (h) decrease due to adiabatic expansion. At this time, the pressure (p) drops to the intermediate pressure pm2.

The air K24 discharged from the recharger 10 flows into the heat exchanger 30 and performs the first heat exchange with the air K27 which is the boil-off gas (step 205). Further, at this time, as described in step 202, the air K24 exchanges heat with the liquid air K21 (step 206). By these heat exchanges, the air K24 is cooled to become the air K25. With reference to the ph diagram at this time, the pressure (p) does not change at the intermediate pressure pm2, but the specific enthalpy (h) decreases as the air K24 is cooled.
Note that steps 205 and 206 may be performed in the reverse order. That is, after the step of exchanging heat between the air K24 and the liquid air K21 (step 206 described above), the step of exchanging heat between the air K24 and the air K27 which is the boil-off gas (step 205 described above). May be done. That is, either step 205 or step 206 may come first.

Next, the air K25 discharged from the heat exchanger 30 flows into the heat exchanger 40 and performs a second heat exchange with the air K27, which is a boil-off gas (step 207). As a result, the air K25 is further cooled to become the air K26. With reference to the ph diagram at this time, the pressure (p) does not change at the intermediate pressure pm2, but the specific enthalpy (h) decreases as the air K25 is cooled. Further, it can be seen that the air K26 is cooled to the liquid air temperature and is in a mixed state of gas and liquid.

Next, the air K26 is expanded inside the tank 60 by the expansion valve 50 (step 208). At this time, the temperature of the air K26 drops due to the Joule-Thomson effect. The liquid air K28 that has become liquid is stored in the tank 60. The pressure in the tank 60 at this time is, for example, atmospheric pressure p0. The temperature of the liquid air K28 is, for example, -196 ° C. With reference to the ph diagram at this time, the pressure (p) decreases, but the specific enthalpy (h) is a conserved Joule-Thomson expansion.
Further, the air K27 in a gaseous state without becoming a liquid is utilized as a boil-off gas for heat exchange in the heat exchangers 30 and 40 in the above-mentioned steps 205 and 207.

Note that step 204 can be regarded as a power generation process in which power is generated by the expansion energy when the liquid air K21 changes from a liquid to a gas.
Further, in steps 202 and 206, the liquid air K21 before the power generation process is heated to change the phase of the air from liquid to gas, and the air after the power generation process is cooled to exchange heat between them. It can be regarded as the heat exchange process of 1.
Further, step 207 is regarded as a second heat exchange step of further cooling the air by exchanging heat with the air after the first heat exchange step and returning at least a part of the air from the gas to the liquid state. be able to.
Then, the power generation operation of the charge power generation system 1 described above can be considered as a power generation method including the power generation step, the first heat exchange step, and the second heat exchange step described above.

In steps 202 and 203, it is preferable that the temperature of the air K22 and the air K23 is higher. This corresponds to the point T21 moving in the direction of the arrow Y21 in the ph diagram of FIG. Further, the intermediate pressure pm2 is preferably made smaller. This corresponds to the point T22 moving in the direction of the arrow Y22 in the ph diagram of FIG. By doing so, the energy recovery efficiency of the rechargeable power generation system 1 is further improved.

The charging power generation system 1 of the present embodiment is characterized in that the boil-off gas is mixed with the air K11 taken in from the outside air at the time of charging. As a result, as described above, the energy recovery efficiency of the charging power generation system 1 can be improved, and impurities contained in the air K11 can be removed.

Further, the charging power generation system 1 of the present embodiment is characterized in that, at the time of power generation, the liquid state is changed to a gas state, and the air after the power generation is subsequently cooled and reliquefied as liquid air. That is, since the air K24 after power generation has a large amount of cold heat, the cold heat can be recovered by reliquefying at least a part thereof. As a result, it is possible to suppress wasteful release of cold heat as compared with the conventional method of releasing the air after power generation to the outside air, and the energy recovery efficiency of the charge power generation system 1 is improved.
Then, the charging power generation system 1 of the present embodiment utilizes the air K27, which is a boil-off gas, for heat exchange in the heat exchangers 30 and 40 in steps 205 and 207. That is, it is possible to suppress the wasteful release of the cold heat of the boil-off gas to the outside air. Therefore, the energy recovery efficiency of the rechargeable power generation system 1 can be further improved.
Further, in the ph diagram of FIG. 5, the intermediate pressure pm2 and the maximum pressure ph2 are set smaller than the saturation pressure pc. That is, pc> pm2 and pc> ph2. However, the present invention is not limited to this, and the intermediate pressure pm2 and the maximum pressure ph2 may be set larger than the saturation pressure pc. That is, pc <pm2 and pc <ph2 may be set.

FIG. 6 is a diagram showing a ph diagram of a conventional charging power generation system during power generation.
As shown in the figure, in the conventional rechargeable power generation system, at the time of power generation, the air after power generation is released to the outside air.
On the other hand, in the pf diagram of the charging power generation system 1 of the present embodiment shown in FIG. 5, power is generated by incorporating the processes after step 205 into the ph diagram shown in FIG. At least a part of the air K24 after the above is reliquefied.
Further, in the ph diagram of the charging power generation system 1 of the present embodiment shown in FIG. 5, the air K27, which is a boil-off gas, is added to steps 205 and 207 with respect to the ph diagram shown in FIG. Incorporates the process of utilizing for heat exchange in the heat exchangers 30 and 40.

The rechargeable power generation system 1 of the present embodiment does not use a special chemical material as compared with the method using a storage battery or hydrogen. Therefore, the running cost tends to be low. In addition, since flammable members are not used, safety can be improved.
Further, the rechargeable power generation system 1 of the present embodiment stores energy by using liquid air having a smaller volume as compared with the method of storing electric power as compressed air. Therefore, the energy storage density is high, and the device constituting the charging power generation system 1 can be miniaturized.
Further, since the charging power generation system 1 of the present embodiment uses the air K24 after power generation to turn the liquid air into a gas state, the use of external heat can be further reduced. Normally, the external heat is sufficient from the heat supplied from the atmosphere at room temperature. Therefore, it is not necessary to use the exhaust heat of the boiler, the electric heater, the solar heat, etc. as in the conventional case.
Furthermore, the charging power generation system 1 of the present embodiment does not require fuel for combustion. Therefore, CO ₂ emissions can be suppressed.
In the rechargeable power generation system 1 of the present embodiment, basically two heat exchangers, a heat exchanger 30 and a heat exchanger 40, are sufficient. Therefore, the device configuration of the charging power generation system 1 can be simplified and the economic efficiency can be improved.

Further, the rechargeable power generation system 1 at the time of power generation can be regarded as a heat engine that uses the following thermal cycles (a) to (d) according to the ph diagram of FIG.
(A) Work process that uses the expansion energy when a fluid such as air changes from liquid to gas (b) First heat exchange between the fluid before the work process and the fluid after the work process Heating process to heat the fluid before the work process (c) First cooling process to cool the fluid after the work process by the first heat exchange (d) Second to the fluid after the first cooling process A second cooling process that further cools the fluid by exchanging heat and returns at least part of the fluid from a gas to a liquid state.

The following thermal cycles (e) to (f) can also be added.
(E) Expansion process that returns the fluid to a liquid state by expanding the fluid discharged from the second cooling step (f) Pressurization process that pressurizes the liquid before the expansion process.

The work process of (a) corresponds to step 204 in the above example. That is, the expansion energy when the liquid air K21 changes from a liquid to a gas causes the turbine 10c to rotate and the generator 10d to operate, thereby corresponding to the process of generating electricity.
The heating process of (b) corresponds to step 202 in the above example. That is, in the heat exchanger 30, the liquid air K21 exchanges heat with the air K24 to correspond to the process of heating the liquid air K21.
The first cooling process of (c) corresponds to step 205 and step 206 in the above-mentioned example. That is, in the heat exchanger 30, the liquid air K21 exchanges heat with the air K24 to correspond to the process of cooling the air K24.
The second cooling process of (d) corresponds to step 207 in the above example. That is, in the heat exchanger 40, the air K25 exchanges heat with the air K27, which is a boil-off gas, and corresponds to the process of forming the air K26.
The expansion process of (e) corresponds to step 208 in the above example. That is, the air K26 expands inside the tank 60 by the expansion valve 50, and at this time, the temperature of the air K26 decreases due to the Joule-Thomson effect.
The pressurizing process of (f) corresponds to step 201 in the above example. That is, it corresponds to the process of boosting the pressure and sending out the liquid air K21 by using the pump P.

In the actual process, the thermal cycles (a) to (f) proceed in the order of (f) → (b) → (a) → (c) → (d) → (e).
It should be noted that performing work here is to generate electricity in the above-mentioned example, but as another example, it also corresponds to performing work to rotate an engine or a motor as a power source.

<Explanation of control of charge power generation system 1>
Next, the control of the charge power generation system 1 performed by the control unit 80 will be described. Here, a temperature sensor (not shown) for measuring the temperature of the air K13 and K25 flowing between the heat exchanger 30 and the heat exchanger 40, and a pressure sensor (not shown) for measuring the pressure are installed. A case where the control unit 80 performs control based on the temperature and pressure obtained from these will be described. However, the present invention is not limited to this, and temperature sensors and pressure sensors may be installed at other locations and control may be performed based on the temperature and pressure obtained from these sensors. Further, control may be performed based not only on the temperature and pressure but also on, for example, the flow rate of air acquired from the flow rate sensor, the amount of liquid air acquired from the level sensor installed in the tank 60, and the like.
(Operation during charging)
FIG. 7A is a flowchart showing the control of the charging power generation system 1 at the time of charging.
First, the control unit 80 acquires the temperature of the air K13 from the temperature sensor (step 301). Next, the control unit 80 acquires the pressure of the air K13 from the pressure sensor (step 302).
Then, the control unit 80 sets the target pressure from the acquired temperature (step 303). The target pressure may be obtained by using a predetermined calculation formula for obtaining the target pressure from the temperature. A LUT (Look up Table) in which the temperature and the target pressure are paired is prepared, and this LUT is prepared. It may be obtained by referring to.

Next, the control unit 80 determines whether or not the pressure acquired in step 302 is within a predetermined range from the target pressure (step 304).
As a result, if it is within the predetermined range (Yes in step 304), the electric power input to the motor 10a is maintained (step 305).
On the other hand, if it is not within the predetermined range (No in step 304), the electric power applied to the motor 10a is adjusted (step 306). Specifically, when the acquired pressure is larger than the target pressure, the electric power applied to the motor 10a is reduced. As a result, the rotation speed of the motor 10a is reduced, and the pressure can be expected to decrease toward the target pressure. On the other hand, when the acquired pressure is smaller than the target pressure, the electric power applied to the motor 10a is increased. As a result, the rotation speed of the motor 10a increases, and the pressure can be expected to increase toward the target pressure. Further, the amount of change in electric power may be increased or decreased according to the difference between the acquired pressure and the target pressure.

(Operation during power generation)
FIG. 7B is a flowchart showing the control of the charge power generation system 1 at the time of power generation.
First, the control unit 80 acquires the temperature of the air K25 from the temperature sensor (step 401). Next, the control unit 80 acquires the pressure of the air K25 from the pressure sensor (step 402).
Then, the control unit 80 sets the target pressure from the acquired temperature (step 403). The target pressure can be set in the same manner as in step 303 of FIG. 7 (a).

Next, the control unit 80 determines whether or not the pressure acquired in step 402 is within a predetermined range from the target pressure (step 404).
As a result, if it is within the predetermined range (Yes in step 404), the electric power input to the pump P is maintained (step 405).
On the other hand, if it is not within the predetermined range (No in step 404), the electric power applied to the pump P is adjusted (step 406). Specifically, when the acquired pressure is larger than the target pressure, the electric power input to the pump P is reduced. On the other hand, when the acquired pressure is smaller than the target pressure, the electric power input to the pump P is increased.

During charging and power generation, the control unit 80 performs the above control, and by repeating this, feedback control can be performed.

Next, a modified example of the charging power generation system 1 will be described.
<Modification example 1>
8 (a) to 8 (b) are views showing a first modification of the charge power generation system 1.
The illustrated charging power generation system 1 is different from the charging power generation system 1 shown in FIG. 1 in that the charging generator 10 is divided into a compression device 11 and a power generation device 12, and is the same except for the above.
That is, the charging / generating system 1 shown in FIG. 1 operates the compressor 10b by rotating the motor 10a at the time of charging, and compresses the air K11. Further, at the time of power generation, the turbine 10c is rotated by the air K23 and the generator 10d is operated to generate power. The motor 10a and the generator 10d are the same device and are shared.
On the other hand, in the charge power generation system 1 of FIG. 8, the compression device 11 operates and the generator 12 does not operate at the time of charging shown in FIG. 8 (a). In this case, by rotating the motor 10a of the compressor 11, the compressor 10b is operated to compress the air K11. Further, at the time of power generation shown in FIG. 8B, the generator 12 operates and the compression device 11 does not operate. In this case, the air K23 rotates the turbine 10c of the generator 12 to operate the generator 10d to generate electricity. In this case, the motor 10a and the generator 10d are separate devices. The shafts of the compression device 11 and the generator 12 are separate, and the recharger 10 is a biaxial device.

<Modification 2>
9 (a) to 9 (b) are views showing a second modification of the charge power generation system 1.
The illustrated charging power generation system 1 is different from the charging power generation system 1 shown in FIG. 1 in that a heat exchanger 91 is added, and is the same except for the addition.
Water is flowing into the heat exchanger 91, and the air K19 and K22 exchange heat with the water. As a result, the air K19 and K22 are heated by water. That is, in the charging power generation system 1 shown in FIG. 1, for example, at the time of power generation, the liquid air K21 and the air K22 were heated by the heat exchanger 30, the heat storage device 20, and the external heat, but the charging in FIG. 9 is performed. In the power generation system 1, heating can be further performed by the heat exchanger 91.
The water used in the heat exchanger 91 is not particularly limited, but for example, it is normal temperature water, and tap water, well water, industrial water, cooling water, and the like can be used. The cooling water is usually used for cooling equipment and the like, but in this case, the temperature is sufficiently higher than that of the air K19 and K22. Therefore, the air K19 and K22 can be heated.
Further, the heat exchanger 91 may be installed between the heat storage device 20 and the turbine 10c. As a result, even larger expansion energy can be applied to the air K23.

<Modification example 3>
10 (a) to 10 (b) are views showing a third modification of the charge power generation system 1.
The illustrated charging power generation system 1 is different from the charging power generation system 1 shown in FIG. 1 in that a heat exchanger 92 is added, and is the same except for the addition.
_{LN 2} (liquid nitrogen) and LNG (Liquefied Natural Gas) flow into the heat exchanger 92, and the air K13 and K25 exchange heat with the _{LN 2 and LNG.} As a result, the air K13 and K25 are further cooled by _{LN 2 and LNG.} That is, in the charge power generation system 1 shown in FIG. 1, the air K12 and K24 were cooled by the heat exchanger 30, but in the charge power generation system 1 of FIG. 9, the air K13 and K25 discharged from the heat exchanger 30 were used. Is further cooled by the heat exchanger 92. That is, the heat exchanger 92 assists in cooling.

<Modification example 4>
11 (a) to 11 (b) are views showing a fourth modification of the charge power generation system 1.
The illustrated charging power generation system 1 is different from the charging power generation system 1 shown in FIG. 1 in that the heat exchanger 30 is divided into a heat exchanger 31 and a heat exchanger 32, and the others are the same. ..
That is, in the rechargeable power generation system 1 shown in FIG. 1, for example, at the time of power generation, in the heat exchanger 30, the air K24 exchanges heat with the liquid air K21 and the air K27 which is a boil-off gas and is cooled. .. On the other hand, in the charging power generation system 1 of FIG. 11, the air K24 is first cooled by exchanging heat with the air K27, which is a boil-off gas, in the heat exchanger 31. Further, the air K24 exchanges heat with the liquid air K21 in the heat exchanger 32 and is cooled. That is, in the rechargeable power generation system 1 of FIG. 11, the function of the heat exchanger 30 is shared between the heat exchanger 31 and the heat exchanger 32.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.
In this embodiment, the charging power generation system 1 shown in FIG. 1 was used to charge and generate power. In addition, nitrogen was used as the fluid.
At the time of charging, the charging power generation system 1 was operated by the method as described with reference to FIGS. 1 (a) and 2 to charge the electric power. At this time, 141 kJ / kg of electric power was applied to liquefy the nitrogen to obtain liquid nitrogen (LN ₂ ). Since the liquefaction rate of nitrogen at this time was 25%, 564 kJ / LN ₂ kg was required as the electric power for producing 1 kg of liquid nitrogen.
At the time of power generation, the charge power generation system 1 was operated by a method as described with reference to FIGS. 1 (b) and 4 to generate power. The electric power generated at this time was 111 kJ / kg. Since the liquefaction rate of nitrogen at this time was 50%, the electric power generated by consuming 1 kg of liquid nitrogen is 222 kJ / LN ₂ kg.
Therefore, the reciprocating efficiency is as high as 222/564≈39%. That is, it can be seen that the charge power generation system 1 is excellent in energy recovery efficiency.

Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the description of the claims that the above-described embodiment with various modifications or improvements is also included in the technical scope of the present invention.

1 ... rechargeable power generation system, 10 ... rechargeable generator, 20 ... heat storage device, 30, 31, 32, 40, 91, 92 ... heat exchanger, 50 ... expansion valve, 60 ... tank, 70 ... mixing valve, 80 ... control Department

Claims (17)

A power generation means that generates electricity by the expansion energy when a fluid changes from a liquid to a gas,
By heating the fluid before it flows into the power generation means, the fluid is phase-changed from a liquid to a gas, and the fluid after being discharged from the power generation means is cooled and heat exchange is performed between them. 1 heat exchange means and
A second heat exchange means that further cools the fluid by exchanging heat with the fluid discharged from the first heat exchange means and returns at least a part of the fluid from a gas to a liquid state.
Power generation device equipped with. Further provided with an expansion means for returning the fluid to a liquid state by expanding the fluid discharged from the second heat exchange means.
The power generation device according to claim 1, wherein the second heat exchange means exchanges heat with the fluid in a gaseous state that remains without becoming a liquid by the expansion means. 2. The fluid after being discharged from the power generation means is further cooled by exchanging heat with the fluid in a gaseous state that does not become a liquid but remains as a liquid by the expansion means. The power generation device described in. The power generation device according to claim 1, wherein the fluid before flowing into the power generation means is heated by external heat other than heat generated by the own device in addition to the first heat exchange means. Further equipped with heat storage means to store heat,
The power generation device according to claim 1, wherein the fluid before flowing into the power generation means is heated by heat accumulated in the heat storage means in addition to the first heat exchange means. The gas that remains without becoming a liquid by the expansion means is sent to an external device that utilizes the cold heat of the fluid after exchanging heat with the fluid after being discharged from the power generation means. Item 2. The power generation device according to item 2. A compression means that uses electric power to compress a fluid in a gaseous state and stores compression energy in the fluid.
A heat exchange means for cooling the fluid compressed by the compression means by performing heat exchange, and a heat exchange means.
An expansion means that expands the fluid discharged from the heat exchange means to change at least a part of the fluid from a gas to a liquid state.
A mixing means that mixes the fluid in a gaseous state that remains without becoming a liquid by the expanding means with the fluid before flowing into the compression means.
A charging device equipped with. A power generation process that uses the expansion energy when a fluid changes from a liquid to a gas to generate electricity.
In the first heat exchange step, in which the fluid is phase-changed from a liquid to a gas by heating the fluid before the power generation step, the fluid is cooled after the power generation step, and heat is exchanged between them. ,
A second heat exchange step of further cooling the fluid by exchanging heat with the fluid after the first heat exchange step and returning at least a part of the fluid from a gas to a liquid state.
Power generation method equipped with. A compression process that uses electric power to compress a fluid in a gaseous state and stores compression energy in the fluid.
A heat exchange step of cooling the fluid compressed by the compression step by performing heat exchange, and a heat exchange step.
An expansion step of expanding the fluid after the heat exchange step to change at least a part of the fluid from a gas to a liquid state.
A mixing step of mixing the fluid in a gaseous state that remains without becoming a liquid in the expansion step with the fluid before the compression step.
Charging method with. An operation that switches between a power generation operation in which power is generated by the expansion energy when a fluid changes from a liquid to a gas and a charging operation in which the fluid in a gaseous state is compressed by using electric power and the compressed energy is stored in the fluid. Means and
When the power generation operation is performed, the fluid is phase-changed from a liquid to a gas by heating the fluid before flowing into the operating means, and the fluid after being discharged from the operating means is cooled. The first heat exchange means for exchanging heat between
A second heat exchange means that further cools the fluid discharged from the first heat exchange means and returns at least a part of the fluid from a gas to a liquid state when the power generation operation is performed.
A rechargeable power generation system equipped with. Further provided with an expansion means for returning the fluid to a liquid state by expanding the fluid discharged from the second heat exchange means.
When performing the charging operation, the second heat exchange means cools the fluid by exchanging heat with the fluid in the state of a gas remaining without becoming a liquid by the expansion means. The rechargeable power generation system according to claim 10. When the charging operation is performed, the fluid after being discharged from the operating means is cooled by exchanging heat with the fluid in the state of a residual gas that does not become a liquid by the expanding means. 11. The rechargeable power generation system according to claim 11. The charging power generation according to claim 11, further comprising a mixing means for mixing the fluid in a gaseous state remaining without being turned into a liquid by the expanding means with the fluid before flowing into the operating means. system. Further equipped with heat storage means to store heat,
The heat storage means
When performing the charging operation, heat generated from the operating means is stored,
The rechargeable power generation system according to claim 10, wherein when the power generation operation is performed, the fluid before flowing into the operating means is heated by the accumulated heat. The work process of doing work using the expansion energy when a fluid changes from a liquid to a gas,
A heating process in which the first heat exchange is performed between the fluid before the work process and the fluid after the work process to heat the fluid before the work process, and
The first cooling process of cooling the fluid after the work process by the first heat exchange, and
A second cooling process in which the fluid is further cooled by performing a second heat exchange with the fluid after the first cooling process, and at least a part of the fluid is returned from a gas to a liquid state.
A heat engine that uses a heat cycle with. The heat engine according to claim 15, further comprising an expansion process of returning the fluid to a liquid state by expanding the fluid discharged from the second cooling process. The heat engine according to claim 15, further comprising a pressurizing process for pressurizing a liquid before the work process.

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