Novel energy storage liquid cooling plate based on jet oscillator and design method thereof

Abstract

The invention discloses a novel energy storage liquid cooling plate based on a jet oscillator and a design method of the novel energy storage liquid cooling plate based on the jet oscillator, and belongs to the technical field of energy storage liquid cooling plate design. And the cooling liquid entering the rear half section of the liquid cooling plate is periodically oscillated in a mixing chamber of the jet oscillator, so that the bottom of the heating battery cell is subjected to a convective heat exchange mode of periodic high-flow-speed back-and-forth oscillation sweeping, the flow speed of convective heat exchange is relatively high, and the contact area is relatively large due to periodic sweeping, so that the heat exchange efficiency of the battery cell is greatly improved. Therefore, the heat exchange performance is well improved, and the problem that the temperature difference exists before and after the battery cell group is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage liquid cooling plate design, and specifically relates to a novel energy storage liquid cooling plate based on a jet oscillator and a design method thereof. Background Art

[0002] At present, in energy storage systems, the battery cells generate a lot of heat during charging and discharging. If the heat is not discharged, the battery cell temperature will be too high, affecting the service life of the battery cell and may even cause a fire. When designing energy storage systems, the mainstream heat dissipation systems are divided into two methods: air cooling and liquid cooling. The liquid cooling system uses the convection heat dissipation principle of liquid to drive the circulation of coolant through the liquid cooling unit, and the heat generated inside the energy storage device is taken away by the coolant. The coolant then returns to the liquid cooling unit to cool down and continue to flow. In the liquid cooling system of the energy storage device, the liquid cooling plate is a component for heat exchange between the coolant and the heating element of the energy storage device. Its design and material selection have an important impact on the heat dissipation effect of the system.

[0003] At present, the selection of liquid cooling plate materials is mainly based on cheap and easy-to-process aluminum alloys, which can meet the thermal conductivity requirements. In the design of the liquid cooling plate flow channel, the existing flow channel adopts a multi-branch design. Starting from the right water inlet, the flow channel is 2-3 vertical branches along the tail end of the liquid cooling plate, and then turns at the tail end and vertically along the water inlet. There will be 1-2 series branches in the main channel loop, and all branches will converge at the middle of the tail end of the liquid cooling plate to flow to the left rear half of the flow channel. In the left half of the flow channel, it will still be divided into 2-3 vertical branches along the water outlet, and more connecting branches are added between the branches to increase the contact area between the coolant and the battery cell in the flow channel. There is an obvious problem with the existing flow channel design. The temperature of the coolant entering the water inlet is relatively low, so the cooling effect of some battery cells on the right side is better. When it reaches the left side, the coolant has absorbed part of the heat and the overall heat load becomes smaller. At this time, the cooling effect of the coolant will be reduced, causing the temperature of the battery cells on the left to be 1-2 degrees higher than that on the right, and the overall temperature uniformity of the battery cells will deteriorate.

[0004] At present, in order to improve the temperature uniformity, the flow control is carried out on the back half of the original liquid cooling plate, and the flow channel of the back half of the liquid cooling plate is made into a whole surface to increase the contact area. In this case, the overall flow rate of the coolant will decrease. Since the liquid cooling is in the form of convection heat transfer, the convection heat transfer coefficient is taken into consideration. When the area becomes larger and the flow rate becomes smaller, the overall heat transfer coefficient becomes smaller, which is not as good as the original flow channel shape. Therefore, when performing flow control, the volume cannot be increased blindly. Summary of the invention

[0005] The present invention provides a novel energy storage liquid cooling plate based on a jet oscillator and a design method thereof. The fluid characteristics of the jet oscillator are utilized to add the jet oscillator to the rear half of the liquid cooling plate, and the flow of the rear half of the liquid cooling plate is controlled, thereby improving the performance of the liquid cooling plate.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions:

[0007] A novel energy storage liquid cooling plate based on a jet oscillator, wherein a jet oscillator is installed on the rear half branch of the liquid cooling plate to control the flow;

[0008] The rear half of the liquid cooling plate is configured with multiple branches according to the number of battery cell groups, each branch is connected to multiple jet oscillators, and the multiple jet oscillators are arranged along a transverse array, and the two branches after the jet oscillators merge and flow toward the water outlet;

[0009] The total width of each column of fluidic oscillators needs to be smaller than the width of a single battery module; the aspect ratio of the fluidic oscillator is greater than 1 and less than or equal to 1.2, the length of the inlet throat of the fluidic oscillator is consistent with the length of the feedback channel, which is approximately 1 / 7 of the overall width, and the width of the mixing chamber is 3 / 7 of the width of the oscillator;

[0010] The water inlet of the front half of the liquid cooling plate is divided into two large branches, one of which is distributed in the front half in a transverse S shape and merges with the other large branch to form a main road for connecting the front half and the rear half of the liquid cooling plate. The merged main road enters the rear half of the liquid cooling plate and is divided into two branches after a 90° bend.

[0011] A small branch in series is arranged on one of the large branches of the front plate of the liquid cooling plate;

[0012] The center line of the jet oscillator coincides with the center line of the rear half of the battery core module.

[0013] The design method of the novel energy storage liquid cooling plate based on the jet oscillator comprises the following steps:

[0014] Confirm the arrangement of the fluidic oscillator according to the arrangement characteristics of the battery cell group to ensure that the flow channel in the bottom liquid cooling plate is in full contact with the battery cell;

[0015] The number and size of the fluidic oscillators are designed according to the desired oscillation frequency and speed of the fluidic oscillators.

[0016] Beneficial effect: The present invention provides a novel energy storage liquid cooling plate based on a jet oscillator and a design method thereof. The fluid characteristics of the jet oscillator are utilized to add the jet oscillator to the rear half of the liquid cooling plate, so that the coolant entering the rear half of the liquid cooling plate is periodically oscillated in the mixing chamber of the jet oscillator, so that the bottom of the heated battery cell is subjected to periodic high-velocity oscillation and sweeping back and forth in a form of convective heat exchange. Since the flow rate of the convective heat exchange is fast and the contact area is large due to the periodic sweeping, the heat exchange performance is greatly improved, thereby solving the problem of temperature difference between the front and rear of the battery cell group. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a liquid cooling plate in an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of a battery cell group applicable to an embodiment of the present invention;

[0019] Figure 3-Figure 14 This is a single cycle motion effect diagram of the entire cyclic sweep of the fluid in the jet oscillator in an embodiment of the present invention;

[0020] In the figure, 1-first branch, 2-second branch, 3-series branch, 4-main branch, 5-third branch, 6-fourth branch, 7-jet oscillator, 8-water inlet, 9-water outlet, 71-upper feedback channel, 72-lower feedback channel, 73-mixing chamber. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0022] The self-excited jet oscillator with dual feedback channels, after the fluid enters the inlet of the oscillating ejector, when it reaches the compression section at the inlet, the flow rate will increase due to the smaller cross-sectional area, and then the fluid enters the interior of the oscillating ejector. The internal area of ​​the oscillator is divided into an upper feedback channel and a lower feedback channel by two J-shaped structures, and the hollow area separated in the middle is named "mixing chamber". After the fluid flows into the mixing chamber, due to the Coanda effect, the main jet will adhere to the upper or lower wall of the mixing chamber, but there is a separation bubble between the upper and lower walls and the jet, so that the main jet is not completely attached to the wall of the mixing chamber. After the main jet passes through the wall, it flows out from the outlet in the opposite direction to the tangential direction of the wall, and part of the jet enters the upper and lower feedback channels after the separation, and is refluxed into the wall separation bubble. With the continuous inflow of the jet, the size of the separation bubble will increase to a certain extent, thereby slowly pushing the main jet to the other side of the wall, and then another feedback channel injects the separation bubble on the other side of the wall, pushing the main jet that has been attached to one side of the wall to the other side, realizing the wall attachment conversion and making the main jet oscillate repeatedly. After repeated cycles, an oscillating jet will be formed at the outlet of the oscillating ejector.

[0023] By utilizing the fluid characteristics of the above-mentioned jet oscillator, this embodiment provides a Figure 1 The new energy storage liquid cooling plate based on the oscillating ejector shown in the figure controls the flow of the rear half of the original liquid cooling plate to improve the performance of the liquid cooling plate. The rear half of the liquid cooling plate is added with the shape of the jet oscillator, so that the coolant entering the rear half of the cold plate is periodically oscillated in the mixing chamber of the jet oscillator. Since the performance of the jet oscillator is strongly related to its shape, its arrangement needs to be considered when it is added. When the liquid cooling plate is used in different scenarios, the specifications and sizes determined are also different, such as Figure 2 As shown, this embodiment is generally applicable to square batteries and is suitable for the most commonly used models in energy storage systems. Taking the liquid cooling plate used in the battery pack of the type 1P52PS as an example, in this type of battery, the battery cells are divided into 4 modules, each module consists of 13 battery cells arranged in a large-surface bonding form, and the four modules are arranged in parallel with an interval of 12mm. According to the arrangement characteristics of the above-mentioned battery cells, the flow channel in the bottom liquid cooling plate needs to be in full contact with the battery cells. If the shape of two oscillators arranged front and back is adopted, the area in contact with the bottom surface of the battery cell in the middle mixing chamber is limited because the upper feedback channel and the lower feedback channel of the oscillator need to be taken into account. According to the feature that the latter two battery cells are also arranged in two columns longitudinally, it is improved to a shape in which two columns of oscillators are arranged vertically, and the center line of the oscillator coincides with the center line of the latter two modules, and then the number of each column is determined according to the size of the oscillator.

[0024] The oscillation period, internal flow rate, and pressure-related physical quantities of the jet oscillator are related to the shape of the oscillator, so the selection of the feedback channel length will affect the frequency and speed of the oscillator, as well as how many oscillators are arrayed on the cold plate. Therefore, the total width of the oscillating jet needs to be smaller than the width of a single battery module, and then the NS equation is formed according to the three-dimensional directional component required for flow control, that is: , , , In the formula, is the fluid density, u, v, w are the velocity components of the fluid in the x, y, and z directions respectively, t is the time, and the function f is the volume force. is the viscosity coefficient and P is the pressure.

[0025] Since the length in the z-axis direction is fixed and the speed in the x-direction, that is, the value of u, is as large as possible, it can be determined that in order to minimize the momentum loss of the flow inside the jet oscillator, the aspect ratio of the jet oscillator is greater than 1 and less than or equal to 1.2; since the main vortex inside the oscillator must go through the development process of formation, extrusion, crushing, and re-formation, the length of the inlet throat is consistent with the length of the feedback channel, which is approximately 1 / 7 of the overall width, and the width of the mixing chamber is 3 / 7 of the width of the oscillator.

[0026] According to the above analysis, a liquid cooling plate based on an oscillating ejector is designed. In this liquid cooling plate, the front half is divided into a first branch 1 and a second branch 2 after coming out of the water inlet 8. A series branch 3 is arranged on the first branch 1. This design is used to make the contact area between the coolant and the upper heating core sufficient, and the straight shape is conducive to reducing the flow resistance. The first branch 1 and the second branch 2 are combined into a main path 4 at the bottom to connect the front half and the rear half of the liquid cooling plate. After the main path 4 enters the rear half, it makes a 90-degree turn and is divided into a third branch 5 and a fourth branch 6. The third branch 5 and the fourth branch 6 are respectively connected to three jet oscillators 7, which are arranged in a horizontal array. Finally, the third branch 5 and the fourth branch 6 are merged into one path to flow to the water outlet 9; the jet oscillator 7 is composed of an upper feedback channel 71, a lower feedback channel 72 and a mixing chamber 73.

[0027] like Figure 3-Figure 14 As shown in the figure, when this liquid cooling plate is working normally, the coolant in the front half is normally heat exchanged through convection heat exchange. Since the temperature of the coolant in the front half is relatively low, the heat exchange efficiency is better. When the coolant reaches the back half, the main jet enters the jet oscillator at a relatively high speed, and then passes through three jet oscillators and flows directly into the outlet. After a few seconds, the separation bubble from the feedback channel begins to form, and the main jet begins to oscillate left and right with a small amplitude according to the Coanda effect. As time goes on, the volume of the separation bubble increases, and the oscillation amplitude of the main jet increases until its amplitude reaches the edge of the mixing chamber and maintains this oscillation amplitude. At this time, the bottom of the heated battery cell undergoes a periodic high-flow rate back-and-forth oscillation sweeping convection heat exchange form. Since the flow rate of convection heat exchange is relatively fast and the contact area is relatively large due to periodic sweeping, the heat exchange performance is better than that of general liquid cooling plates.

[0028] The above are only preferred embodiments of the present invention. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the protection scope of the present invention.

Claims

1. A new type of energy storage liquid cooling plate based on jet oscillator, characterized in that: A jet oscillator is installed on the rear half branch of the liquid cooling plate to control the flow.

2. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 1 is characterized in that: The rear half of the liquid cooling plate is configured as a plurality of branches according to the number of battery cell groups, each branch is connected to a plurality of jet oscillators, the plurality of jet oscillators are arranged along a transverse array, and the plurality of branches after passing through the jet oscillators converge and flow toward the water outlet.

3. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 1 or 2, characterized in that: The total width of each column of fluidic oscillators is smaller than the width of a single battery cell module.

4. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 3 is characterized in that: The center line of the fluidic oscillator coincides with the center line of the battery cell group.

5. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 3 is characterized in that: The aspect ratio of the fluidic oscillator is greater than 1 and less than or equal to 1.

2.

6. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 5 is characterized in that: The length of the jet oscillator inlet throat is consistent with the length of the feedback channel, which is 1 / 7 of the overall width; the width of the mixing chamber is 3 / 7 of the width of the oscillator.

7. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 1 or 2, characterized in that: The water inlet of the front half of the liquid cooling plate is divided into two large branches, one of which is distributed in the front half in a transverse S shape and merges with the other large branch to form a main road for connecting the front and rear half liquid cooling plates. The merged main road enters the rear half liquid cooling plate, and after a 90° bend, it is divided into two branches, each of which is equipped with a jet oscillator.

8. The novel energy storage liquid cooling plate based on the jet oscillator according to claim 6 is characterized in that: A small branch in series is arranged on one of the large branches of the front plate of the liquid cooling plate.

9. The design method of the novel energy storage liquid cooling plate based on the jet oscillator according to any one of claims 1 to 8, characterized in that: The following steps are involved: Confirm the arrangement of the fluidic oscillator according to the arrangement characteristics of the battery cell group to ensure that the flow channel in the bottom liquid cooling plate is in full contact with the battery cell; The number and size of the fluidic oscillators are designed according to the oscillation frequency and speed of the fluidic oscillators required for flow control.

10. The design method of the novel energy storage liquid cooling plate based on the jet oscillator according to claim 9 is characterized in that: According to the three-dimensional directional component form of flow control required by NS equation, that is: ， ， ， The length in the z-axis direction is fixed, so that the x-direction velocity, i.e., the value of u, is large, and the aspect ratio of the jet oscillator is greater than 1 and less than or equal to 1.2; wherein, is the fluid density, u, v, w are the velocity components of the fluid in the x, y, and z directions respectively, t is the time, and the function f is the volume force. is the viscosity coefficient and P is the pressure.

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