Heat pump and method for operating the same

Abstract

To miniaturize a heat pump that uses magneto-caloric effect while maintaining or improving the performance of the heat pump.SOLUTION: A heat pump 10 includes: a heat absorption part 11 for moving heat with a working fluid that includes magnetic particles and causing the working fluid to absorb heat; and a heat radiation part 12 applied with a magnetic field M to cause the working fluid that has absorbed heat to discharge the heat. The heat radiation part 12 includes: a first flow channel 11 through which the working fluid circulates; and an extrusion mechanism 22 installed inside the first flow channel 11 to mechanically extrude the working fluid.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a heat pump utilizing a magnetocaloric effect and a method for operating the same. [Background technology]

[0002] In recent years, new technologies have been proposed to improve the heat exchange efficiency in heat pumps that utilize the magnetocaloric effect (hereinafter referred to as "magnetic heat pumps"). Patent Document 1 describes a technology that uses a magnetic particle dispersion liquid, in which magnetic particles are dispersed in a solvent, as a working fluid that circulates between an area where a magnetic field is not applied (heat absorption section) and an area where a magnetic field is applied (heat dissipation section). With this technology, the heat transfer area between the magnetic particles, which have a very small particle size, and the solvent of the working fluid becomes extremely large, and it is expected that the heat exchange efficiency between them will be improved. A similar technology is also described in Patent Document 2.

[0003] In order to realize such a miniaturization of the magnetic heat pump, it is necessary not only to reduce the size of the device by narrowing the flow path of the working fluid, but also to suppress the associated deterioration of the heat pump performance. For this purpose, it is required to increase the adiabatic temperature change per unit volume of the working fluid due to the magnetocaloric effect. In order to increase the adiabatic temperature change per unit volume of the working fluid due to the magnetocaloric effect, it is possible to increase the content of magnetic particles in the working fluid or to increase the strength of the magnetic field applied to the heat dissipation part. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 085567 [Patent Document 2] International Publication No. 2022 / 168379 Summary of the Invention [Problem to be solved by the invention]

[0005] However, depending on the type and particle size of the magnetic particles, the desired magnetocaloric effect may not be obtained by simply increasing the content in the working fluid. That is, for example, although a large magnetocaloric effect can be obtained depending on the type of magnetic particles, it may be difficult to process them into fine particles while maintaining their function due to the problem of processability. Therefore, the particle size must be made large, and a slurry with low dispersibility of magnetic particles may have to be used as the working fluid. When such a working fluid flows through a narrow flow path under a magnetic field, the magnetic particles in the working fluid are easily attracted to the magnetic field and settle, which may cause the flow path to be blocked. Therefore, in order to suppress the deterioration of heat pump performance due to the miniaturization of the magnetic heat pump described in Patent Documents 1 and 2, a structural measure that can be applied regardless of the dispersion form of the magnetic particles in the working fluid is required.

[0006] Therefore, an object of the present invention is to realize a heat pump utilizing the magnetocaloric effect, while maintaining or improving its performance, and reducing its size. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the heat pump of the present invention is a heat pump that transfers heat by a working fluid containing magnetic particles, and has a heat absorption section that causes the working fluid to absorb heat, and a heat dissipation section to which a magnetic field is applied and causes the working fluid that has absorbed heat to release the heat, wherein the heat dissipation section has a first flow path through which the working fluid circulates, and an extrusion mechanism that is provided within the first flow path and mechanically extrudes the working fluid.

[0008] Furthermore, a method for operating a heat pump of the present invention is a method for operating a heat pump that transfers heat using a working fluid containing magnetic particles, and includes a step of causing the working fluid to absorb heat in a heat absorption section, and a step of causing the working fluid that has absorbed heat to release the heat in a heat dissipation section to which a magnetic field is applied, wherein the step of releasing the heat includes a step of mechanically pushing out the working fluid circulating through the first flow path by an extrusion mechanism provided in a first flow path constituting the heat dissipation section.

[0009] According to such a heat pump, even if magnetic particles in the working fluid are attracted to the magnetic field and settle in the first flow path, the first flow path can be prevented from being blocked by forcing the magnetic particles to flow. Therefore, it is possible to use a slurry with low dispersibility of magnetic particles in order to increase the adiabatic temperature change per unit volume of the working fluid due to the magnetocaloric effect. Effect of the Invention

[0010] According to the present invention, it is possible to achieve miniaturization of a heat pump utilizing the magnetocaloric effect while maintaining or improving the performance thereof. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a magnetic heat pump according to an embodiment of the present invention; [Diagram 2] 3 is a cross-sectional view showing a first configuration example of a heat dissipation section of the present embodiment. FIG. [Diagram 3] 4A and 4B are a plan view and a see-through perspective view showing a second configuration example of the heat dissipation section of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification, the present invention is applied to a heat dissipation section where heat exchange between a working fluid and a heat receiving fluid is performed, but the present invention is not limited thereto, and may be applied to a heat dissipation section where heat exchange between a main working fluid and an auxiliary working fluid is performed, as described in Patent Documents 1 and 2.

[0013] First, the configuration of a magnetic heat pump according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of the magnetic heat pump of this embodiment.

[0014] The magnetic heat pump 10 transfers heat from a heat-donating fluid flowing through a low-temperature side flow path L1 to a heat-receiving fluid flowing through a high-temperature side flow path L2 by using a working fluid containing magnetic particles (particles mainly composed of a material that exhibits a magnetocaloric effect), and has a heat absorption section 11, a heat dissipation section 12, a temperature increase section 13, a temperature decrease section 14, and a pump 15. These are provided in a circulation flow path L10 that circulates the working fluid. The working fluid used here is a dispersion liquid in which magnetic particles are dispersed in a solvent, and the form of the dispersion is not particularly limited, but a slurry is assumed as an example.

[0015] The heat absorption section 11 is composed of a portion of the circulation flow path L10 adjacent to the low-temperature side flow path L1 and a portion of the low-temperature side flow path L1 adjacent to the circulation flow path L10, and has a function of making the working fluid absorb heat by heat exchange between the working fluid flowing through the circulation flow path L1 and the heat-donating fluid flowing through the low-temperature side flow path L2. The heat dissipation section 12 is composed of a portion of the circulation flow path L10 adjacent to the high-temperature side flow path L2 and a portion of the high-temperature side flow path L2 adjacent to the circulation flow path L10, and has a function of dissipating heat to the working fluid by heat exchange between the working fluid flowing through the circulation flow path L1 and the heat-receiving fluid (heat exchange medium) flowing through the high-temperature side flow path L2. The temperature increase section 13 is composed of a portion of the circulation flow path L10 downstream of the heat absorption section 11 and upstream of the heat dissipation section 12. The temperature decrease section 14 is composed of a portion of the circulation flow path L10 downstream of the heat dissipation section 12 and upstream of the heat absorption section 11. The position of the pump 15 is not limited to the position shown in the figure, as long as the pump 15 can perform the function of circulating the working fluid within the circulation flow path L10.

[0016] The magnetic heat pump 10 is configured such that a magnetic field M is applied to the heat dissipation section 12 and the temperature increase section 13, respectively, and a magnetic field M is not substantially applied to the heat absorption section 11 and the temperature decrease section 14, respectively. This makes it possible to increase or decrease the magnetic field M for the working fluid circulating through the circulation flow path L10, and to increase or decrease the temperature of the working fluid by generating a magnetocaloric effect on the magnetic particles in the working fluid. That is, the temperature increase section 12 functions to increase the temperature of the working fluid by applying the magnetic field M to the working fluid, and the temperature decrease section 14 functions to decrease the temperature of the working fluid by removing the magnetic field M that was applied to the working fluid. Note that a magnetic field weaker than the magnetic field M applied to the heat absorption section 11 and the temperature decrease section 14 may be applied to the heat absorption section 11 and the temperature decrease section 14, but it is preferable that a magnetic field is not intentionally applied to them, except for unavoidable ones such as leakage magnetic fields. The source of the magnetic field M is not particularly limited, and for example, an electromagnet may be used, but it is preferable to use a permanent magnet considering that a power source is not required.

[0017] 1, the operation of the magnetic heat pump 10 will be briefly described. For convenience, the description will be given assuming that no magnetic field is applied to the heat absorbing section 11 and the temperature lowering section 14.

[0018] First, the working fluid absorbs heat from the heat-donating fluid flowing through the low-temperature side flow path L1 in the heat absorption section 11 where no magnetic field is applied, and then flows through the circulation flow path L10 and is supplied to the temperature raising section 13. In the temperature raising section 13, a magnetic field M is applied to the working fluid in an adiabatic state, which causes the magnetic moments of the magnetic particles in the working fluid to align and the entropy to decrease. The working fluid thus heated flows through the circulation flow path L10 and is supplied to the heat dissipation section 12 to which the magnetic field M is applied as in the temperature raising section 13. Therefore, the working fluid is maintained in a state where the magnetic field M is applied in the heat dissipation section 12, where it releases heat to the heat receiving fluid flowing through the high-temperature side flow path L2. Then, the working fluid flows through the circulation flow path L10 and is supplied to the temperature lowering section 14. In the temperature lowering section 14, the magnetic field M applied to the working fluid is removed in an adiabatic state, which causes the magnetic moments of the magnetic particles in the working fluid to become random and the entropy to increase. The working fluid whose temperature has been lowered in this manner flows through the circulation flow path L10 and is again supplied to the heat absorption section 11. By repeating such an operation, the magnetic heat pump 10 transfers heat from the heat donor fluid flowing through the low-temperature side flow path L1 to the heat receiving fluid flowing through the high-temperature side flow path L2.

[0019] The illustrated configuration of the magnetic heat pump 10 is merely schematic and does not limit the present invention. In the illustrated example, in the heat absorption section 11, the flow direction of the heat-donating fluid flowing through the low-temperature side flow path L1 is different from the flow direction of the working fluid flowing through the circulation flow path L10, but they may be the same. Similarly, in the illustrated example, in the heat dissipation section 12, the flow direction of the heat-receiving fluid flowing through the high-temperature side flow path L2 is different from the flow direction of the working fluid flowing through the circulation flow path L10, but they may be the same. In addition, in the temperature rise section 13, a magnetic field M may be applied so that its strength increases stepwise or continuously along the circulation flow path L10. In addition, as long as the function of the magnetic heat pump 10 is not impaired, a magnetic field weaker than the magnetic field M applied to the heat dissipation section 12 and the temperature rise section 13 may be applied to the heat absorption section 11 and the temperature drop section 14 as described above.

[0020] Incidentally, in order to realize the miniaturization of the magnetic heat pump, it is necessary not only to reduce the size of the device but also to suppress the associated decrease in heat pump performance. For this purpose, for example, it is possible to increase the content of magnetic particles in the working fluid to increase the adiabatic temperature change per unit volume of the working fluid due to the magnetocaloric effect. However, depending on the type of magnetic particles, although a large magnetocaloric effect can be obtained, the particle size must be made large due to the problem of processability, and therefore, there are cases where a slurry must be used as the working fluid. When such a working fluid flows through a narrow flow path under a magnetic field, the magnetic particles in the working fluid are easily attracted to the magnetic field and settle, which may cause the flow path to be blocked. Therefore, in this embodiment, in order to suppress the occurrence of the above-mentioned problems even when a slurry is used as the working fluid, the heat dissipation unit 12 has the following characteristic configuration.

[0021] Here, two specific configuration examples of the heat radiating section 12 in the magnetic heat pump 10 of this embodiment will be described.

[0022] (First configuration example) 2 is a cross-sectional view showing a first configuration example of the heat dissipation part of this embodiment. Note that the configuration of the heat dissipation part shown in the figure is merely an example and does not limit the present invention. In addition, the arrangement of the heat dissipation part shown in the figure is merely for convenience and does not limit the posture during use.

[0023] The heat dissipation unit 12 has a first flow path L11 that constitutes the circulation flow path L10 and allows the working fluid to flow, and a second flow path L21 that constitutes the high-temperature side flow path L2 and allows the heat-receiving fluid (heat exchange medium) to flow. The first flow path L11 is formed by a circular tube member 21, and the second flow path L21 is formed by a hollow screw 22 arranged inside the circular tube member 21. In other words, the circular tube member 21 and the hollow screw 22 have a double-tube structure, the first flow path L11 is formed in the gap between the circular tube member 21 and the screw 22, and the second flow path L21 is formed inside the screw 22. Although not shown, the heat dissipation unit 12 is provided with a magnetic field generating unit for applying a magnetic field M to the working fluid flowing through the first flow path L11. The magnetic field generating unit is preferably a pair of permanent magnets arranged on both sides of the circular tubular member 21 in the width direction, thereby applying a magnetic field M in a direction intersecting the central axis C1 of the circular tubular member 21, thereby increasing the strength of the magnetic field M applied to the working fluid.

[0024] The screw 22 is provided rotatably around the central axis C1 of the cylindrical member 21 as the axis of rotation, and therefore functions as an extrusion mechanism that mechanically extrudes the working fluid flowing through the first flow path L11 to cause it to flow. Note that "mechanically extruding" here means mechanically extruding the working fluid by contacting it, and does not include extruding it by pressure. With this function of the screw 22, even if the magnetic fluid in the working fluid in the first flow path L11 is attracted to the magnetic field M and settles in the first flow path L11, it can be forcibly caused to flow, thereby preventing the first flow path L11 from being blocked. In this way, since the dispersion form of the magnetic particles in the working fluid is not an issue, it is also possible to use a slurry as the working fluid in order to increase the adiabatic temperature change per unit volume of the working fluid due to the magnetocaloric effect.

[0025] In addition, the second flow passage L21 is provided adjacent to the first flow passage L11, and as long as the heat exchange efficiency between the working fluid flowing through the first flow passage L11 and the heat receiving fluid flowing through the second flow passage L21 can be maintained favorably, the position of the second flow passage L21 is not particularly limited. For example, the second flow passage L21 may be provided adjacent to the radially outer side of the first flow passage L11. That is, another circular pipe member may be provided outside the circular pipe member 21, and the second flow passage L21 may be formed between the outer circular pipe member and the circular pipe member 21. In that case, the screw 22 does not have to be formed hollow. However, if another circular pipe member is provided outside the circular pipe member 21, a magnetic field generating unit must be provided further outside, and the distance from the magnetic field generating unit to the first flow passage L11 becomes longer. This leads to a decrease in the strength of the magnetic field M applied to the working fluid, which is not preferable from the viewpoint of suppressing the decrease in heat pump performance due to miniaturization. Therefore, the screw 22 is preferably formed hollow as shown in the figure so that the second flow passage L21 is formed inside the screw 22.

[0026] In order to further improve the heat exchange efficiency between the working fluid and the heat receiving fluid in the heat dissipation unit 12, the heat dissipation unit 12 may further have a flow path other than the first flow path L11 as a flow path constituting the circulation flow path L10. That is, the heat dissipation unit 12 may further have, for example, a third flow path connected in parallel to the first flow path L11 in the hollow part of the screw 22. Note that "connected in parallel" here means that a part of the working fluid flowing through the circulation flow path L10 flows into the first flow path L11, and the rest flows into the third flow path. It is preferable that the third flow path is formed by a circular tube member and a screw is provided inside the third flow path. This screw, like the screw 22 in the first flow path L11, is provided rotatably with the central axis of the circular tube member constituting the third flow path as the rotation axis, and functions as an extrusion mechanism that mechanically extrudes and flows the working fluid flowing through the third flow path. As a result, even if the magnetic fluid in the working fluid in the third flow path is attracted to the magnetic field M and settles, it can be forced to flow, thereby preventing the third flow path from being blocked.

[0027] The shape of the screw 22 is not particularly limited, and an appropriate shape can be selected depending on the type of working fluid used.

[0028] (Second configuration example) 3(a) and 3(b) are a plan view and a perspective view, respectively, showing a second configuration example of the heat dissipation unit of this embodiment. Note that the configuration of the heat dissipation unit shown in the figure is merely an example and does not limit the present invention. In addition, the arrangement of the heat dissipation unit shown in the figure is merely for convenience and does not limit the posture during use.

[0029] The heat dissipation unit 12 has a first flow path L12 constituting the circulation flow path L10 and a second flow path (not shown) constituting the high temperature side flow path L2. The first flow path L12 is formed by a disk-shaped hollow member 31, and has an inlet 32 ​​provided at the center of the hollow member 31 and an outlet 33 provided at the periphery of the hollow member 31. The second flow path is provided adjacent to the first flow path L12, preferably adjacent to the first flow path L12 in the axial direction of the hollow member 31. This makes it possible to maintain good heat exchange efficiency between the working fluid flowing through the hollow disk-shaped first flow path L12 and the heat receiving fluid flowing through the second flow path. In addition, although not shown, the heat dissipation unit 12 is provided with a magnetic field generating unit for applying a magnetic field M to the working fluid flowing through the first flow path L12. The magnetic field generating unit is preferably a pair of permanent magnets arranged on both axial sides of the hollow member 31 (and the hollow member constituting the second flow path), thereby allowing a magnetic field M to be applied in a direction along the central axis C2 of the hollow member 31, thereby increasing the strength of the magnetic field M applied to the working fluid.

[0030] The heat dissipation unit 12 also has an impeller 34 inside the hollow member 31 that is rotatably provided with its central axis C2 as a rotation axis. The impeller 34 has a function of pushing the working fluid radially supplied from the inlet 32 ​​into the first flow passage L12 outward in the radial direction and discharging it to the outlet 33. As with the screw 22 of the first configuration example, this function of the impeller 34 makes it possible to suppress the first flow passage L12 from being blocked by forcibly flowing the magnetic fluid in the working fluid even if the magnetic fluid is attracted to the magnetic field M and settles in the first flow passage L12. In this way, the dispersion form of the magnetic particles in the working fluid is not an issue, so that it is also possible to use a slurry as the working fluid in order to increase the adiabatic temperature change per unit volume of the working fluid due to the magnetocaloric effect.

[0031] The configuration of the impeller 34, for example, the number and shape of the blades, is not particularly limited as long as it functions as a pushing mechanism that mechanically pushes out the working fluid flowing through the first flow path L12, and an appropriate configuration can be selected depending on the type of working fluid used. The number of outlets 33 of the first flow path L12 is not limited to one as shown in the figure, and may be multiple, and the position of the outlets is not particularly limited as long as they are provided on the peripheral portion of the hollow member 31. [Explanation of symbols]

[0032] 10 Magnetic Heat Pump 11 Heat absorbing part 12 Heat dissipation part 13 Heating section 14 Cooling section 15 Pump 21 Circular pipe members 22 Screw 31 Hollow members 32 Entrance 33 Exit 34 Impeller L1 Low temperature side flow path L2 High temperature side flow path L10 Circulation flow path L11, L12 First flow path L21 Second flow path Central axes of C1 and C2 Magnetic field M

Claims

1. A heat pump that transfers heat by a working fluid containing magnetic particles, a heat absorption section that causes the working fluid to absorb heat; A heat dissipation unit to which a magnetic field is applied and which causes the working fluid that has absorbed the heat to release the heat, The heat pump, wherein the heat dissipation portion has a first flow path through which the working fluid flows, and an extrusion mechanism provided in the first flow path and mechanically extruding the working fluid.

2. The first flow path is formed by a circular pipe member, The heat pump according to claim 1 , wherein the extrusion mechanism comprises a screw that is rotatable about a central axis of the cylindrical member as a rotation axis.

3. The heat pump according to claim 2 , wherein the heat dissipation portion has a second flow path provided adjacent to the first flow path and through which a heat exchange medium that exchanges heat with the working fluid flows.

4. The heat pump according to claim 3 , wherein the screw is hollow so as to have the second flow passage therein.

5. The heat dissipation unit further includes a third flow path through which the working fluid flows, and another pushing mechanism provided in the third flow path and mechanically pushing out the working fluid, the third flow path is constituted by a circular tube member provided in a hollow portion of the screw, The heat pump according to claim 4 , wherein the other extrusion mechanism is composed of a screw that is rotatable about a central axis of the cylindrical member that constitutes the third flow path as a rotation axis.

6. The heat pump according to claim 2 , wherein the heat dissipation portion is configured so that the magnetic field is applied in a direction intersecting a central axis of the circular tubular member that constitutes the first flow path.

7. the first flow path is formed of a disk-shaped hollow member and has an inlet provided in a center portion of the hollow member and an outlet provided in a peripheral portion of the hollow member, 2. The heat pump according to claim 1, wherein the pushing mechanism comprises an impeller that is rotatable about a central axis of the hollow member as a rotation axis and pushes the working fluid supplied from the inlet radially outward and discharges it from the outlet.

8. The heat pump according to claim 7 , wherein the heat dissipation portion has a second flow path provided adjacent to the first flow path in the axial direction of the hollow member and through which a heat exchange medium that exchanges heat with the working fluid flows.

9. The heat pump according to claim 7 or 8, wherein the heat dissipation section is configured so that the magnetic field is applied in a direction along a central axis of the hollow member that constitutes the first flow path.

10. The heat pump according to claim 1 , wherein either no magnetic field is applied to the heat absorption section, or a magnetic field weaker than the magnetic field applied to the heat radiation section is applied to the heat absorption section.

11. The heat pump according to claim 1, wherein the working fluid that has absorbed heat in the heat absorption section is supplied to the heat dissipation section, and the working fluid that has released heat in the heat dissipation section is supplied to the heat absorption section, thereby circulating the working fluid between the heat absorption section and the heat dissipation section.

12. The heat pump according to claim 1 , wherein the working fluid is a slurry in which the magnetic particles are dispersed in a solvent.

13. A method for operating a heat pump that transfers heat by a working fluid containing magnetic particles, comprising: A step of absorbing heat in the working fluid in a heat absorption section; A step of discharging the heat to the working fluid that has absorbed the heat in a heat dissipation section to which a magnetic field is applied, A method for operating a heat pump, wherein the step of releasing the heat includes a step of mechanically pushing out the working fluid circulating through the first flow path by an extrusion mechanism provided in the first flow path constituting the heat dissipation section.

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