Device for transferring thermal energy to a fluid

Abstract

The present invention relates to a device (1) for transferring thermal energy to a fluid, comprising a heat exchanger (2) arranged in a flow path (4) spatially limited by a housing (3), the heat exchanger (2) having a plurality of flow channels (6) through which a fluid can pass along a main flow direction (5), the heat exchanger (2) having a heat storage capacity capable of temporarily storing thermal energy, and a fluid having a relatively high energy and a fluid having a relatively low energy flowing alternately through the heat exchanger (2). The present invention also relates to a method of using said device (1).

Description

[Technical Field]

[0001] The present invention relates to a device (regenerative heat exchanger) for transferring thermal energy into or to a fluid using a heat exchanger arranged in a flow path spatially limited by a housing. The heat exchanger has a plurality of flow channels through which fluid can pass along a main flow direction. The heat exchanger has a heat storage capacity capable of temporarily storing a certain amount of thermal energy.

[0002] The present invention also relates to a method of using the device. [Background technology]

[0003] In addition to conventional heat exchangers (recuperators), regenerators can also be used for heat exchange between two fluids or for heat recovery. They consist essentially of a porous or channeled heat storage medium. In the heating stage, the first or warm fluid flows through the thermal storage device and is heated. In this process, the (first) fluid is cooled. In the cooling stage, the stored heat is released into a second or colder fluid.

[0004] This technique is used, for example, for general ventilation of buildings or enclosed rooms. The so-called push-pull heat exchangers used for ventilating buildings consist of a pipe with a ceramic material with channels as a heat storage medium and a fan that can switch the transport direction. This unit is installed on the exterior wall of a building, transports warm indoor air (exhaust air) to the outside, and after switching the transport direction, transports cool outdoor air (fresh air) into the room. This uses heat from the exhaust air to preheat the fresh air.

[0005] To ensure high heat recovery efficiency, it is necessary to ensure good heat transfer between the heat accumulator and the fluid. The amount of surface available for heat exchange and the heat transfer coefficient of the flow within the heat exchanger are decisive factors here. The duration of the period of heating or cooling the heat exchanger must be adapted to the thermal capacity of the thermal storage device, for example to prevent further discharge air, especially warm discharge air, from being carried through the thermal storage device when the maximum thermal capacity is reached.

[0006] The regenerators known from the prior art of such heat exchangers are usually made of ceramic material. This is disadvantageous, for example, because of the high manufacturing costs. Furthermore, ceramics have properties that do not require their use in ventilation systems for buildings or vehicles, such as resistance to high temperatures and corrosive media. Additionally, design options for channel geometry are very limited, adversely affecting the amount of heat transfer between the fluid and the matrix, the possible efficiency, and the operating range of the heat exchanger. Another disadvantage is that air humidity is adsorbed and desorbed in the porous ceramic. This occurs especially near the dew point.

[0007] To heat or air condition the interior of a battery electric vehicle, the necessary energy must be drawn from the vehicle battery. This reduces the vehicle's range when the outside temperature is high or low. Here, the use of a heat exchanger such as a regenerator can keep energy requirements to a minimum, thereby increasing range. Summary of the Invention

[0008] It is therefore an object of the present invention to at least partially solve the problems described in the prior art and in particular to provide a device that allows the transfer of thermal energy between fluids, in particular from a fluid with a higher energy level to a fluid with a lower energy level.

[0009] This object is achieved by the features of the independent claims. Advantageous further embodiments are defined in the dependent claims. Features individually recited in the claims may be combined with each other in any way and / or with features of the specification. The specification describes the invention with particular reference to the figures, which show additional embodiments.

[0010] An apparatus for transferring thermal energy into or to a fluid is provided, the apparatus including a heat exchanger arranged in a flow path spatially limited by a housing, the heat exchanger having a plurality of flow channels through which a flow can pass along a main flow direction, the heat exchanger having a heat storage capacity capable of temporarily storing a certain amount of thermal energy, and a fluid having a relatively high energy and a fluid having a relatively low energy flowing or being able to flow through the heat exchanger alternately.

[0011] The amount and / or time of thermal energy that can be temporarily stored may be specified or defined with reference to the operation of the device. In particular, means can be provided for predetermining the temporal and / or volumetric flows through the device, so that the required heat storage capacity of the heat exchanger can also be predetermined or defined.

[0012] The device can be used, for example, for ventilation and / or temperature regulation of buildings or for ventilation and / or temperature regulation of the interior of a vehicle. The flow path may be formed by a pipe or may be formed by an air duct, for example in a motor vehicle. The heat exchanger is arranged in a flow path for the flow of a fluid, in particular air. As the first air and / or warm air flows through the heat exchanger, the heat exchanger can absorb and at least temporarily store heat or thermal energy. As the second air and / or the cooler air flows through the heat exchanger, the second air and / or the cooler air may absorb heat or thermal energy temporarily stored in the heat exchanger. Similarly, other energy contained in the fluid, such as the enthalpy of vaporization of air humidity, can be temporarily stored in a heat exchanger as heat or thermal energy.

[0013] This allows heat or thermal energy to be absorbed from indoor air, particularly stale air, and transferred to fresh air supplied from outside. Therefore, the energy loss during air exchange can be reduced.

[0014] The heat exchanger preferably has a counter flow direction when heat or thermal energy is released and when heat or thermal energy is absorbed, thereby improving heat transfer to the air. The heat exchanger is preferably designed so that heat or thermal energy flows in the opposite direction, thereby improving heat transfer to the air.

[0015] Depending on the sequence of heat transfer steps, the fresh air supplied from the outside can be heated or cooled. In addition to heat transfer between the exterior and interior air, the air flow may also pass through or through heated components, such as the vehicle's power electronics and / or battery, where the waste heat generated can be used to heat fresh air inside the vehicle.

[0016] The fluids that can flow through the heat exchanger have different temperature levels. The fluid may be warmer due to a higher energy level, or it may be cooler due to a lower energy level. Heat or thermal energy is transferred from a fluid to a heat exchanger as the fluid flows through the heat exchanger, and then transferred back to the fluid from the heat exchanger as a fluid with a lower energy level flows through the heat exchanger.

[0017] The flow path may have or be fluidly connected to a transport device capable of transporting fluid through the flow path. A suitable transport device may be, for example, a fan arranged in the flow path. Alternatively, the fan of the vehicle air conditioning or vehicle ventilation system may also be used to direct the fluid flow, particularly the fluid flow of interest, through the heat exchanger.

[0018] The heat exchanger may be formed (at least in part) from a plurality of foils, the foils being at least in part structured, and the foils being stacked one on top of the other to form a stack. A preferred embodiment is characterized in that the foils that are stacked to form the stack are in particular wrapped and / or twisted around at least one axis of rotation.

[0019] In this way, a matrix can be created that has a large surface area that can be wetted by a fluid and multiple flow channels through which the fluid can flow between the individual foils. The foil then also acts as a heat reservoir, absorbing heat or thermal energy from the first and / or warm fluid and finally releasing heat or thermal energy to the second and / or cold fluid as it flows through the foil.

[0020] The foil may be made of metal or plastic. Metal or plastic foils are easy and cheap to manufacture. The material properties can be particularly easily adapted to the respective field of application, allowing heat exchangers to be manufactured precisely to suit specific purposes.

[0021] At least one of the foils is electrically conductive and may be conductively connected to a voltage source. A conductive foil can be used to achieve additional heating through the flowing fluid. The foil can be heated by connecting it to a voltage source or by using an ohmic resistor. Electrical isolation between the current-carrying foil and adjacent foils can be achieved by adjacent non-conductive foils. These may, for example, be made of a non-conductive material and coated with a non-conductive coating.

[0022] The heat exchanger may be made of a composite material in which some materials have relatively high thermal conductivity and some have relatively low thermal conductivity.

[0023] This particularly helps to reduce heat conduction within the carrier material, which can reduce the efficiency of the regenerator. Preferably, the material with high thermal conductivity is separated at short intervals in the direction of flow, so that good efficiency can be achieved even when using a material with high thermal conductivity.

[0024] It may also be useful if the material has a relatively high thermal conductivity and is divided into several sections along the main flow direction. This can be achieved, for example, by a foil with slots. The main flow direction may in particular extend at least partly parallel to the longitudinal axis of the device, the heat exchanger and / or the housing.

[0025] The structured portion of the foil may have cross-section-narrowing or turbulence-generating structures that allow for the occurrence of throttling of the fluid flow in the flow direction. This allows you to narrow down the target flow. The restriction can be used to improve heat exchange between the flowing fluid and the channel walls or to induce a phase change in the fluid. The turbulation structures can be designed asymmetrically to have different degrees of effectiveness in the two flow directions. Heat exchangers with integrated throttles are particularly advantageous in refrigerator designs as they can also perform the function of the throttle.

[0026] The heat exchanger and the throttle can be formed from a common part. This reduces the number of parts required and can greatly simplify the system or device. This is particularly advantageous when used in refrigeration systems.

[0027] According to a further aspect, there is provided a method of heating or cooling a room using an apparatus (as described herein), wherein a hot fluid, in particular a first fluid, flows through a heat exchanger and transfers thermal energy of the (hot) fluid to the heat exchanger, and thereafter a cold fluid, in particular a second fluid, flows through the heat exchanger and transfers thermal energy stored in the heat exchanger to the (cold) fluid. This reduces the energy required for heating or air conditioning, thereby extending the driving range of a battery electric vehicle.

[0028] The device provided here is particularly intended to improve the driving range of battery electric vehicles, as less energy is needed from the battery to ventilate, cool and heat the interior of the vehicle. By utilizing waste heat from vehicle drive components such as the battery, power electronics and electric drive motor, energy requirements can be further reduced, which also has a positive effect on driving range.

[0029] Technical details and / or modes of operation specified in connection with an apparatus may also be used to characterize a method, and vice versa. In particular, an apparatus may be configured to perform the methods, or the methods may be performed using the apparatus provided herein.

[0030] The invention and the technical environment will now be described in detail with reference to the drawings. Although the drawings show a particularly preferred embodiment of the present invention, the present invention is not limited to this embodiment. In the drawings, the same parts are given the same reference numerals. The following figures show examples and circuit diagrams. [Brief explanation of the drawings]

[0031] [Figure 1] A building equipped with a device for transferring thermal energy. [Figure 2] FIG. 2 is a cross-sectional view of a heat exchanger of the device. DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 shows a building 15 in which an apparatus 1 for transferring thermal energy is arranged. The device 1 includes a flow channel 4 having a first opening 16 and a second opening 17 . The first opening 16 is located inside the building 15 and the second opening 17 is located outside the building 15 . The flow path 4 extends from a room 13 in the building 15 to an exterior area 18 of the building 2 . The transport device 7 and the heat exchanger 2 are arranged in the flow path 4 . The heat exchanger 2 extends along a longitudinal axis 14 and has a plurality of flow channels 6 . The flow channels 6 extend parallel to the longitudinal axis 14 or main flow direction 5 . The heat exchanger 2 extends a length 19 along a longitudinal axis 14 .

[0033] The transport device 7 can generate an air flow 20 in the flow path 4 . The transport device 7 is operable to allow air to be used to enter the flow path 4 from a room 13 of the building 15 through a first opening 16, flow through the heat exchanger 2 and exit the flow path 4 through a second opening 17 to an external area 18. In this case, the first opening 16 functions as an intake port, and the second opening 17 functions as an exhaust port. When the air to be used flows through the flow path 4 from the first opening 16 to the second opening 17, the heat exchanger 2 can temporarily store heat energy from the air flow or the used air.

[0034] The transport device 7 can then operate to allow fresh air to enter the flow path 4 from the external area 18 through the second opening 17, flow through the heat exchanger 2 and exit the flow path 4 through the first opening 16 into the room 13 of the building 15. In this case, the second opening 17 functions as an intake port, and the first opening 16 functions as an exhaust port. When fresh air flows through the flow path 4 from the second opening 17 to the first opening 16, the heat exchanger 2 can transfer the temporarily stored thermal energy to the airflow or fresh air. This preheats the fresh air entering the building 15.

[0035] FIG. 2 shows a cross-sectional view of the heat exchanger 2 taken along the line II-II shown in FIG. The heat exchanger 2 is arranged in a housing 3 . The heat exchanger 2 includes a plurality of structured foils 9 and a smooth foil 8 . The structured foils 9 and the smooth foils 8 are alternately stacked to form two stacks 10, which are then wrapped around the heat exchanger 2 around a rotating shaft 11, so that the foils 8, 9 form a plurality of flow channels 6. At least one of the foils 8 , 9 is electrically conductive and is (conductively) connected to a voltage source 12 . [Explanation of symbols]

[0036] 1 device 2 Heat exchanger 3. Housing 4 Flow path 5 Mainstream direction 6 Flow Channel 7 Transport equipment 8 Smooth foil 9. Structured Foil 10 Laminate 11 Rotation axis 12 Voltage Source 13 rooms 14 Longitudinal Axis 15 Buildings 16 First Opening 17 Second opening 18 External area 19 Length 20 Airflow

Claims

1. 1. A device (1) for transferring thermal energy to a fluid, comprising: a heat exchanger (2) arranged in a flow path (4) spatially limited by a housing (3), the heat exchanger (2) having a plurality of flow channels (6) through which a flow can pass along a main flow direction (5), the heat exchanger (2) having a heat storage capacity capable of temporarily storing thermal energy, and a fluid having a relatively high energy and a fluid having a relatively low energy alternately flowing through the heat exchanger (2).

2. 2. The device (1) according to claim 1, characterized in that the flow path (4) comprises or is fluidly connected to a transport device (7) capable of transporting a fluid through the flow path (4).

3. 3. The device (1) according to claim 1 or 2, characterized in that the heat exchanger (2) is formed from a plurality of foils (8, 9), the foils (8, 9) being at least partially structured and the foils (8, 9) being stacked one on top of the other to form a stack (10).

4. 4. Device (1) according to claim 3, characterized in that the foils (8, 9) stacked one on top of the other to form the stack (10) are wrapped or twisted around at least one axis of rotation (11).

5. 5. Device (1) according to claim 3 or 4, characterized in that the foils (8, 9) are made of metal or plastic.

6. Device (1) according to any one of claims 3 to 5, characterized in that at least one of the foils (8, 9) is electrically conductive and is conductively connected to a voltage source (12).

7. 7. The device (1) according to any one of the preceding claims, characterized in that the heat exchanger (2) is made of a composite material comprising a material with a relatively high thermal conductivity and a material with a relatively low thermal conductivity.

8. 8. The device (1) according to claim 7, characterized in that the material having a relatively high thermal conductivity is divided into a plurality of sections along the main flow direction (5).

9. 9. The device (1) according to any one of the preceding claims, characterized in that the structured portions of the foils (8, 9) have cross-section reduction structures or turbulence generation structures that allow the generation of a throttle of the fluid flow in the flow direction.

10. A method for heating, cooling or ventilating a room (13) using a device (1) according to any one of claims 1 to 9, characterized in that a hot fluid flows through the heat exchanger (2) and transfers its thermal energy to the heat exchanger (2), and then a cold fluid flows through the heat exchanger (2) and transfers the thermal energy stored in the heat exchanger (2) to the cold fluid.

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