EP3740727A1

EP3740727A1 - Heat exchanger system

Info

Publication number: EP3740727A1
Application number: EP19700040.9A
Authority: EP
Inventors: Holger Wuest; Andreas Burghardt
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-01-18
Filing date: 2019-01-03
Publication date: 2020-11-25
Also published as: WO2019141517A1; DE102018200792A1; JP2021511477A; CN111566417A; US20210071919A1

Abstract

The invention relates to a heat exchanger system comprising a hear exchanger device (1), which has elastocaloric elements (11) made of elastocaloric material and is designed to move the elastocaloric elements (11), as a result of which said elements are deformed, so that an elastocaloric effect is achieved, and a vibrating unit (2), which generates mechanical vibrations. Additionally, a vibration transfer device (3) is provided which is arranged between the vibrating unit (2) and the heat exchanger device (1) and transfers the vibrations from the vibrating unit (2) into the elastocaloric elements (11) so that the elastocaloric elements (11) move.

Description

description

title

System for heat exchange

The invention relates to a system for heat exchange with a

Vibration transmitter using the elastocaloric effect. In addition, the invention relates to a heat pump with such a system for

Heat exchange.

State of the art

The elastocaloric effect describes an adiabatic temperature change of a material when the material is subjected to a mechanical force and deforms, for example. The mechanical force or the deformation causes a transformation of the crystal structure, also called phase, in the material. The phase transformation leads to an increase in the temperature of the material. If the released heat is dissipated, the temperature is lowered and the entropy decreases. If then the mechanical force is removed, in turn, a reverse phase transformation (reverse transformation) is caused, which leads to a lowering of the temperature of the material. When heat is applied to the material, entropy increases again.

After the approximately adiabatic phase transformation, the temperature is above the starting temperature. The resulting heat can be dissipated, for example, to the environment and the material then decreases

Ambient temperature. Now, if the phase-to-phase conversion is initiated by reducing the mechanical force to zero, the result is a lower one

Temperature as the starting temperature. Temperature differences can be achieved between maximum temperature after the phase transformation and minimum temperature after the back conversion (at previous heat release) of up to 40 ° C. Materials that show the elastocaloric effect are called elastocaloric materials. Such elastocaloric materials are, for example, shape memory alloys which have superelasticity. Superelastic alloys are characterized by the fact that they return to their original shape even after strong deformation.

Superelastic shape memory alloys have two distinct phases (crystal structures): austenite is the room temperature stable phase and martensite is stable at lower temperatures. Mechanical deformation causes a phase transformation of austenite to martensite, which results in adiabatic temperature rise. The increased temperature can now be released into the environment in the form of heat, which leads to a decrease in entropy. When the elastocaloric material is relieved again, martensite-to-austenite is reconverted, accompanied by adiabatic temperature reduction.

In the following, two typical devices for heat exchange are described: In one arrangement, a biconvex heat conducting element, i. on

Heat conducting element which is convex on both sides, arranged at a distance between two planar Wärmeleitelementen. In each case a elastocaloric element is stretched in the spaces between the planar heat conducting elements and the biconvex heat conducting element. The elastocaloric elements are interconnected and can be moved together. In this case, they are arranged so that in each case a elastocaloric element is deformed by the biconvex heat conducting element, which causes a tensile stress on the convex outer side of the sheet and on the concave inner side a compressive stress. Only in the so-called neutral fiber no stress occurs. At the same time, the other elastocaloric element, owing to its superelasticity, reforms back into its planar original shape and comes into contact with the planar heat-conducting elements in a planar manner. Should the

Reverting to the original shape is incomplete upon contact with the planar heat-conducting element residual reshaping. Through this

Arrangement, heat is transported from the planar heat conducting elements to the biconvex heat conducting element. The heat is typically provided by a heat transfer agent, e.g. B. a coolant, which is in contact with the heat-conducting elements, transported away from the heat-conducting or promoted towards these. For conveying the heat transport medium, a compressor or a pump is usually used. During operation, this delivery component generates

mechanical vibrations. In this document, components that generate mechanical vibrations are called vibrating aggregates.

Disclosure of the invention

A system for heat exchange is proposed. The system comprises a per se known heat exchange device comprising elastocaloric elements of elastocaloric material. The heat exchange device is arranged to move the elastocaloric elements. The movement of the elastocaloric elements deforms them. Triggered by the deformation, the elastocaloric effect occurs in the elastocaloric material, which leads to a heating of the elastocaloric elements. When the elastocaloric elements move back, the elastocaloric cools

Elements during recovery from.

In addition, the proposed system for heat exchange on a vibrating unit. This vibrating unit is z. B. a compressor or a pump for conveying a heat transport medium, for. As a coolant or the like. Typically, a vibrating aggregate is already present in connection with the heat exchanging device to transfer the heat converted by the elastocaloric effect from the device to the heat exchanger

Dissipate heat exchange. The oscillating unit generates mechanical vibrations during its operation.

In addition, a vibration transmitter is provided, which is arranged between the oscillating unit and the device for heat exchange. The vibration transmitter is set up, the vibrations of the

vibrating aggregate to the elastocaloric elements of the device for heat exchange, so that the elastocaloric elements move. In this case, the vibration transmitter, the vibration alone to the elastocaloric elements, only to the heat conducting elements or both to the elastokalorischen elements and transferred to the heat-conducting elements, which leads in each case to the above-described movements of said components. The vibration transmitter allows the

Vibrations of the typically existing oscillating

To pass on aggregates in usable form as movement to the elastocaloric elements. This can add an extra drive for the

elastocaloric elements are dispensed with.

The vibration transmitter transmits primarily vibrations whose deflection points in the direction of movement of the elastocaloric elements or the heating elements. Since the vibrating aggregate typically generates vibrations simultaneously in different or even all directions, provision may be made for the elastocaloric elements to be arranged around the vibrating aggregate in the different directions, in particular in all directions in which the vibrating aggregate generates vibrations.

According to one aspect, the device for heat exchange may additionally comprise heat conducting elements. In the movement of the elastocaloric

Elements can attach the elastocaloric elements to the solid

Heat-conducting elements are moved to and / or away from these or both the elastocaloric elements and the heat-conducting elements are moved in the direction of the other and / or in opposite directions. As a result of the movement of the elastocaloric elements, the elastocaloric elements come into contact with the heat-conducting elements and the elastocaloric elements are deformed. When the elastocaloric elements move back, the elastocaloric elements cool during recovery.

In addition, the vibration transmitter transmits the vibrations of the vibrating aggregate at least to the elastocaloric elements, so that the elastocaloric elements and the heat-conducting elements move toward one another and / or move away from one another. It can the

Vibration transmitter vibration only to the elastocaloric elements or both to the elastocaloric elements and to the

Transfer thermal conduction, which leads to each of the already described above movements of said components. According to one aspect, the vibration transmitter comprises mechanical transmission elements, such. B. spring elements or other mechanical transmission elements having a suitable stiffness. Via the mechanical transmission elements, the vibrations can be transmitted linearly to the elastocaloric element. This is particularly advantageous if the oscillations are regular, ie have a constant amplitude and a constant frequency. This is the case, for example, when the oscillating unit is stationary operated at an operating point.

In addition, irregular oscillations of the oscillating aggregate, whose amplitude and / or frequency vary, can be utilized for the device for heat exchange. For the operation of the

Elastokalorischen elements are an intended travel and a

to comply with the proposed transmitted force. In addition, the

Vibration transmitter be configured to convert the frequency of the mechanical vibrations of the vibrating unit in a suitable frequency for the operation of the device for heat exchange. The frequency may preferably be in a resonant frequency of the device for

Heat exchange are converted, with a particularly high efficiency can be achieved. In the following, measures are presented with which from the irregular vibrations of the oscillating unit of the intended travel and the intended force can be achieved and the frequency of the vibrations are converted into a suitable for the operation of the device for heat exchange frequency.

The vibration transmitter may be a Stellwegbegrenzer, z. B. one

Stop, comprise, which limits the deflection of the vibrations to the intended for the operation of the device for heat exchange travel. As a result, always the same travel can be achieved with irregular vibrations.

In addition, the vibration transmitter, a damping element, for. B. include a spring or a hydraulic element to the forces in the

Transmission of the vibration occur and which can occur to different degrees due to irregular amplitudes of the vibrations, too dampen. As a result, different pronounced deformations of the elastocaloric elements can be prevented.

Preferably, sensors may be provided which perform measurements on the oscillating unit and / or on the vibration transmitter.

Below are exemplary measurements listed, with individual, multiple and / or other measurements that are not listed here, can be performed:

A measurement of the frequency of the mechanical vibrations of the

oscillating aggregate;

a measurement of the force transmitted by the vibrating aggregate;

A measurement of the forces exerted on the elastocaloric elements

Deformation;

- A measurement of the travel.

The measurements can be used to set or optionally control the operation of the heat exchange system for these parameters. For example, the cycles in which the heat transport medium is conveyed may be adjusted or optionally regulated in synchronism with the vibrations transmitted from the vibrating aggregate and transmitted from the vibration transmitter, and optionally altered.

The vibration transmitter can comprise means for changing a pressure within the vibration transmitter, ie in particular a pump, with which the irregular vibrations can be used to build up a negative pressure or to build up an overpressure. The structure of the negative pressure or the overpressure can take place step by step, each vibration individually contributing to the build-up of the negative pressure or the overpressure and, for example via a valve and / or a

Stellwegbegrenzer be controlled. The constructed oppression or

Overpressure can then act on a linearly movable transmission element which is connected to the elastocaloric elements. In the case of

Under negative pressure, the transmission element can move into a volume in which the negative pressure is built up, and in the case of overpressure, move out of a volume in which the overpressure is built up. The The transfer element transfers its pressure-induced movement to the elastocaloric elements. By presetting the pressure, the force provided for operating the device for heat exchange and the resulting deformation of the elastocaloric elements and by the stepwise build-up of the pressure the appropriate frequency can be realized.

In addition, it can be provided that after the desired pressure has been built up and thus the intended force has acted on the elastocaloric elements, the pressure is reduced in a controlled manner via a relief valve. This allows the elastocaloric elements to return to their original shape. The sequence between building up and reducing the pressure can be performed cyclically and optionally controlled by means of a pressure sensor and / or the above-mentioned sensors.

The vibration transmitter may include means for converting the vibrations into electrical work. For this purpose, the oscillation can be transmitted to a permanent magnet enclosed by a coil, which then makes periodic movements into and out of the coil. The electrical work can take the form of electrical energy in one

Energy storage, z. In a battery. In addition, the vibration transmitter may comprise at least one actuator, which then converts the electrical work into a movement of the elastocaloric elements.

In addition, a heat pump is proposed which the

has the above-mentioned system for heat exchange. The above features and advantages of the device also apply to the heat pump. The system for heat exchange can be dispensed with an additional drive within the heat pump, so this more compact and

can be realized cheaper.

The heat pump can be used, for example, in refrigerators / freezers, in the temperature management of Li-ion batteries and solid-state batteries, as well as for heating or cooling the interior of vehicles, etc., to name just a few examples. Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Figure 1 shows a schematic representation of an embodiment of the system according to the invention for heat exchange.

FIG. 2 shows a schematic illustration of a first embodiment of a vibration transmitter from FIG. 1.

FIG. 3 shows a schematic representation of a second embodiment of the vibration transmitter from FIG. 1.

FIG. 4 shows a schematic illustration of a third embodiment of the vibration transmitter from FIG. 1.

FIG. 5 shows a schematic representation of a fourth embodiment of the vibration transmitter from FIG. 1.

Embodiments of the invention

1 shows a schematic representation of an embodiment of the system according to the invention for heat exchange, which comprises a device 1 for heat exchange. The heat exchange device 1 comprises elastocaloric elements 11 of elastocaloric material and

Heat conducting 12 on. In this embodiment, the

elastocaloric elements 11 cyclically moved toward the solid heat conducting elements 12, whereby the elastocaloric elements 11 with the

Wärmeleitelementen 12 come into contact and deformed, so that a elastocaloric effect is achieved, and then of the

Heat conducting 12 moves away. In further embodiments, the heat-conducting elements 12 can be moved and the elastocaloric elements 11 remain fixed or both the elastocaloric elements 11 and the heat-conducting elements 12 are moved. The system for heat exchange also has a vibrating unit 2, such as a compressor or a pump for delivering a

Heat transport means 21, which generates mechanical vibrations. In this case, on the one hand, when the oscillating unit 2 is operated stationarily in one operating point, regular oscillations with a constant amplitude and frequency and on the other hand irregular oscillations whose amplitude and frequency vary can be generated.

According to the invention, a vibration transmitter 3 can be arranged between the oscillating unit 2 and the device 1 for heat exchange. The vibration transmitter 3 is adapted to transmit the mechanical vibrations of the vibrating aggregate 2 to the elastocaloric elements 11 and / or the heat-conducting elements 12 of the heat exchange device 1, so that the elastocaloric elements 11 and the heat-conducting elements 12 cyclically move towards and away from each other , In the following embodiments, the vibration transmitter 3, which is formed in the same manner transmits the vibration alone to the

Elastokalorischen elements 11, which then move on the solid Wärmeleitelemente 12, with these come into contact, thereby deform and move away from the latter. In further embodiments, the vibration transmitter 3 can transmit the vibrations alternatively or additionally to the heat conducting elements 12, so that they move. The construction and the function of the vibration transmitter will be explained in detail in connection with the further FIGS. 2 to 4.

In addition, sensors 4 are provided, which are the frequency of the mechanical vibrations of the oscillating unit 2, a transmitted from the vibrating unit 2 force, one of elastocaloric

Measure elements 11 applied strain and / or a travel. Their arrangement and the function are also explained in connection with the further figures 2 to 4. An electronic computing device 5 is connected to the

Vibration transmitter 3 and the sensors 4 and connected to the oscillating unit 2 and regulates the system for heat exchange by means of the measured variables from the sensors 4. For example, the cycles in which the heat transporting means 21 is conveyed are synchronous with the Vibrations emitted by the vibrating aggregate 2 and by the

Vibration transmitter 3 were transmitted, set.

FIGS. 2 to 5 show three embodiments of the vibration transmitter 3. Identical reference symbols indicate identical components, these will only be explained in detail once. In these embodiments, the

Heat conducting 12 fixed and the elastocaloric elements 11 are moved. In further embodiments, the vibration transmitter is formed in the same way, the elastocaloric elements 11 are fixed and the heat conducting elements 12 are moved. Although, for purposes of illustration in these figures, only one elastocaloric element 11 is shown, the

Description should but for a Elastokalorisches element 11, several

Elastokalorische elements 11 or all elastocaloric elements 11 of the device for heat exchange apply.

FIG. 2 shows a first embodiment of the vibration transmitter 3, which has a mechanical transmission element in the form of a spring element 300. This embodiment is particularly well suited if the oscillating unit 2 generates regular oscillations with the same amplitude and the same frequency. The spring element 300 is selected according to the requirements of the device 1 for heat transport and the parameters of the regular oscillation. An additional control within the Schwingungsüberträgers 3 is not necessary for this case. The deflected in the direction of the spring element 300 mechanical vibrations of the

oscillating unit 2 are received by the spring element 300 and transmitted from this linearly to a transmission element 301. The

Spring element 300 additionally serves as a damping element for damping the forces that occur during the transmission of the vibration. A first sensor 41 is provided which measures the force transmitted to the spring element 300 and the frequency of the transmitted vibrations. The transmission element 301 is in communication with the elastocaloric element 11. In a deflection of the spring element 300, the movement by means of the

Transfer element 301 transmitted to the elastocaloric element 11. There is provided a stop 302 for the spring element 300, which limits the deflection of the spring element 300 to a designated travel. If the spring element 300 expands due to the oscillation, the elastocaloric element will expand Element 11 is moved by the intended travel in the direction of a heat conducting element 12, not shown here, and comes into contact therewith. As the spring member 300 contracts, the elastocaloric member 11 is moved in the opposite direction. The travel of the

Movement of the elastocaloric element 11 and / or the deformation of the elastocaloric element 11 are measured by a second sensor 42.

Figures 3 and 4 show a second and a third embodiment of the Schwingungsüberträgers 3, each having a pump 310, with which the pressure p in a pressure cylinder 311 can be changed. These

Embodiments are particularly well suited when the vibrating aggregate 2 generates irregular vibrations of varying amplitude and frequency. In the second embodiment of Figure 3, the pump 310 is by the mechanical vibrations of the

oscillating unit 2 operates and generates step by step a suppression in the pressure cylinder 311. A check valve 312 is provided to control the change of the pressure p. In other words, any small vibration (in the proper direction to operate the pump) will result in a decrease in pressure p, which will eventually add up to a desired negative pressure. The pressure p in the pressure cylinder is measured by means of a pressure sensor 41. From a predetermined suppression, a linearly movable transmission element 313, which is connected to the elastocaloric element 11, in the

Pressure cylinder 311 pulled in, so that the elastocaloric element 11 is moved to the heat conducting member 12 and comes into contact therewith. In a third exemplary embodiment in FIG. 4, an overpressure is generated in the pressure cylinder 311 instead of the negative pressure. The overpressure is the

Transmission member 313 moves out of the printing cylinder 311 addition. Again, the elastocaloric element 11 is moved to the heat conducting element 12 and comes into contact with this. Via a relief valve 314 am

Pressure cylinder 311, the pressure p in the pressure cylinder 311 is subsequently compensated again and the transmission element 313 moves back to its original position. In both embodiments, the pump 310 and the expansion valve 314 may be adjusted or regulated by means of the measured pressure. FIG. 5 shows a fourth embodiment of the vibration transmitter 3, which has a coil 320 and a permanent magnet 321, which convert the vibrations into electrical work, and an actuator 323. These

Embodiment is also particularly well suited when the oscillating unit 2 generates irregular vibrations of varying amplitude and different frequency. The in the direction of the permanent magnet

321 deflected mechanical vibrations of the oscillating unit 2 are passed to the permanent magnet 321, which then moves into the interior of the coil 320 and / or moved out of this. Due to the changing magnetic flux, a voltage is induced by a

Voltage measuring device 44 is measured. A resulting from the induced voltage electrical energy is in an energy storage 322, z. B. in a battery stored. Accordingly, the energy storage 322 is also charged by small vibrations that move the permanent magnet 321 only over a short distance. The electrical energy from the energy storage

322 is used to operate an actuator 323, which is a

Transmission element 324 which is connected to the elastocaloric element 11, wherein the actuator 323 by means of the sensors 41, 42, 44 can be adjusted or regulated. The actuator 323 moves the transfer member 324 so that the elastocaloric member 11 is cyclically moved toward and in contact with a heat conducting member 12, not shown, and subsequently moved in the opposite direction.

Claims

claims

1. system for heat exchange comprising:

a heat exchange device (1) comprising elastocaloric elements (11) of elastocaloric material and arranged to move the elastocaloric elements (11) so as to deform the elastocaloric elements (11) so as to obtain an elastocaloric effect; and

a vibrating unit (2) generating mechanical oscillations, characterized by a vibration transmitter (3) arranged between the oscillating unit (2) and the heat exchanging device (1) and detecting the vibrations of the unit

vibrating aggregate (2) to the elastocaloric elements (11) transmits, so that the elastocaloric elements (11) move.

2. System according to claim 1, characterized in that the device (1) for heat exchange heat conducting elements (12) and is arranged to move the elastocaloric elements (11) and the heat conducting elements (12) towards each other, whereby the elastocaloric elements (11 ) are brought into contact with the heat conducting elements (12) and deformed, so that a elastocaloric effect is achieved, and / or to move away from each other; and

characterized in that the vibration transmitter (3) the

Vibrations of the oscillating unit (2) transmits at least to the elastocaloric elements (11), so that the

elastocaloric elements (11) and the heat-conducting elements (12) move towards each other and / or move away from each other.

3. System according to claim 1 or 2, characterized in that the

Vibration transmitter (3) comprises mechanical transmission elements (300).

4. System according to claim 3, characterized in that the

Vibration transmitter (3) comprises a Stellwegbegrenzer (302) which limits the deflection of the oscillations to a provided for the operation of the device (1) for heat exchange travel.

5. System according to any one of claims 3 or 4, characterized in that the vibration transmitter (3) comprises a damping element in order to dampen forces that arise in the transmission of the vibration.

6. System according to one of the preceding claims, characterized in that the vibration transmitter comprises means (310) for changing a pressure (p).

7. System according to one of the preceding claims, characterized in that the vibration transmitter (3) comprises means (320, 321) for converting the vibrations into electrical work and at least one actuator (323), which converts the electrical work into a movement of the elastocaloric elements, includes.

8. System according to any one of the preceding claims, characterized by sensors (4, 41, 42) showing the frequency of the mechanical

Vibrations of the vibrating aggregate (2), one of the

vibrating unit (2) transmitted force, one to the

Elastokalorischen elements (11) measure applied strain and / or a travel.

9. System according to one of the preceding claims, characterized

in that the vibration transmitter (3) is set up to convert the frequency of the mechanical vibrations of the oscillating unit into a frequency suitable for the operation of the device (1) for heat exchange.

10. System according to claim 9, characterized in that the

Vibration transmitter (3) is set, the frequency of

to convert mechanical vibrations of the vibrating aggregate into a resonant frequency of the heat exchange device (1).

11. Heat pump comprising a system for heat exchange according to one of claims 1 to 10.