A power battery cooling structure

Abstract

The present invention discloses a power battery cooling structure, including a water tank, a water pump and a pipeline, wherein a heat-conducting medium is placed in the water tank, a water outlet and a first water return port are provided on the water tank, the pipeline is fixed on the battery module, and one end of the pipeline is connected to the water outlet of the water tank through the water pump, and the other end is connected to the first water return port of the water tank, and the cross-sectional area of ​​the inner diameter of the pipeline gradually decreases from one end connected to the water outlet of the water tank to the other end. The structure has a high heat exchange efficiency and can reduce the energy consumption of the air conditioning system.

Description

Technical Field

[0001] The present invention relates to the field of battery cooling, and in particular to a power battery cooling structure. Background Art

[0002] Pure electric vehicles and hybrid electric vehicles use batteries as power sources. They can achieve zero pollution during use and can use other non-petroleum resources such as coal and hydropower. They can effectively solve automobile pollution and energy problems, and therefore have received widespread attention worldwide. The performance and quality of these vehicles depend to a large extent on the performance of the power battery packs they are equipped with. Temperature is a crucial factor affecting the performance of power batteries. When the vehicle is running under different driving conditions, the battery will discharge at different rates and generate a lot of heat at different heat generation rates. In addition, time accumulation and spatial influence will produce uneven heat accumulation, resulting in complex and variable temperature of the battery pack.

[0003] In addition, when the temperature of the battery pack is too high, the battery capacity, life and energy efficiency will be reduced. If the heat accumulated in the battery cannot be dissipated in time, thermal runaway will occur. In severe cases, the battery is in danger of violent expansion and explosion. Therefore, the battery temperature must be controlled for the power lithium battery to keep its operating temperature in an optimal range.

[0004] A heat exchange tube is fixed on the existing battery module, and a heat-conducting medium is contained in the heat exchange tube to facilitate temperature control of the battery module. This structure has low heat exchange efficiency, resulting in that the temperature of the battery module is difficult to control. Summary of the invention

[0005] The present invention provides a power battery cooling structure, which solves the problem of poor heat exchange effect of existing heat exchange tubes.

[0006] The technical means adopted by the present invention are as follows:

[0007] A power battery cooling structure comprises a water tank, a water pump and a pipeline, wherein a heat-conducting medium is placed in the water tank, a water outlet and a first water return port are provided on the water tank, the pipeline is fixed on a battery module, one end of the pipeline is connected to the water outlet of the water tank through the water pump, and the other end is connected to the first water return port of the water tank, and the cross-sectional area of ​​the inner diameter of the pipeline gradually decreases from one end connected to the water outlet of the water tank to the other end.

[0008] Furthermore, it also includes a three-way valve I, a three-way valve II and a three-way joint; the water tank is provided with a second water return port;

[0009] The first interface of the three-way valve I is connected to the water outlet of the water tank, and the second interface is connected to the water inlet of the water pump;

[0010] The first interface of the three-way valve II is connected to the water outlet of the water pump, the second interface is connected to the second water return port of the water tank, and the third interface is connected to the first interface of the three-way joint;

[0011] The second interface of the three-way connector is connected to the pipeline, and the third interface is connected to the third interface of the three-way valve I.

[0012] Furthermore, the pipeline includes a main water outlet pipe, a heat exchange pipe and a main water return pipe;

[0013] The heat exchange tubes include heat exchange tube I and heat exchange tube II arranged side by side;

[0014] One end of the main water outlet pipe is connected to the water outlet of the water tank, and the other end is connected to the water inlet ends of the heat exchange tube I and the heat exchange tube II;

[0015] One end of the main water return pipe is connected to the first water return port of the water tank, and the other end is connected to the water outlet ends of the heat exchange tube I and the heat exchange tube II;

[0016] The heat exchange tube is fixed on the battery module, and the flow directions of the heat-conducting medium in the heat exchange tube I and the heat exchange tube II are opposite.

[0017] Furthermore, the inner walls of the heat exchange tubes I and II are provided with raised vortex wings.

[0018] Furthermore, the vortex wing includes a first spoiler and a second spoiler connected to each other, the angle formed at the connection between the first spoiler and the second spoiler is not greater than 90°, and the sharp angle formed by the first spoiler and the second spoiler is consistent with the direction in which the cross-sectional area of ​​the inner diameter of the pipeline decreases.

[0019] Furthermore, the heat exchange tube I and the heat exchange tube II are flat tubes, a flat surface on one side of the flat tube is fixed on the surface of the battery module, and the vortex wing is arranged on the inner walls of the two flat surfaces of the flat tube.

[0020] Furthermore, aluminum oxide nanoparticles are provided in the heat conducting medium.

[0021] Furthermore, there are a plurality of battery modules, each of which is respectively fixed with a group of heat exchange tubes, and the main water outlet pipe is connected to the heat exchange tubes through a plurality of branch water outlet pipes;

[0022] The main water return pipe is connected to the heat exchange pipe via a plurality of branch water return pipes;

[0023] The branch water outlet pipes are all provided with temperature control flow meters, and the branch water return pipes are all provided with temperature sensors.

[0024] Furthermore, the number of the battery modules is more than 8, the branch water pipes include a primary branch water pipe and a secondary branch water pipe, and the number of the primary branch water pipes is an odd number;

[0025] The branch return water pipes include a primary branch return water pipe and a secondary branch return water pipe, and the number of the primary branch return water pipes is an odd number.

[0026] Furthermore, one end of the branch water outlet pipe is a first bend, which is connected to the main water outlet pipe, and one end of the branch water return pipe is a second bend, which is connected to the main water return pipe.

[0027] Compared with the prior art, the power battery cooling structure described in the present invention has the following advantages: since the inner diameter of the pipe fixed on the battery module for heat exchange is a reducer, when the heat-conducting medium flows in the pipe, the temperature of the heat-conducting medium will be further reduced, so as to improve the heat exchange efficiency between the heat exchange pipe and the battery module, and ensure that the battery module operates within a suitable temperature range. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a structural diagram of the power battery cooling structure disclosed in the present invention;

[0029] Figure 2 It is the structural diagram of the heat exchange tube;

[0030] Figure 3 This is a structural diagram of the first form of fixing the heat exchange tube on the battery module;

[0031] Figure 4 This is a structural diagram of a second form of fixing the heat exchange tube on the battery module, and the figure only shows the structural diagram of the form of arrangement on the upper surface of the battery module;

[0032] Figure 5a It is a structural diagram of the inner part of the pipeline with vortex wings;

[0033] Figure 5b is an axial view of the interior of a pipeline with vortex wings;

[0034] Figure 5c is the structural diagram of the vortex wing;

[0035] Figure 6 A structural diagram of a plurality of battery modules;

[0036] Figure 7 This is a structural diagram of a second embodiment of the power battery cooling structure disclosed in the present invention;

[0037] Figure 8 A schematic diagram of the flow of the heat transfer medium when used to cool the battery module in the second embodiment;

[0038] Fig. 9 This is a schematic diagram of the flow of the heat-conducting medium when the second embodiment is used to heat the battery module;

[0039] Fig.10 An embodiment of connecting a main water outlet pipe, a branch water outlet pipe, a main water return pipe and a branch water return pipe when there are 8 battery modules;

[0040] Fig.11 An embodiment of connecting a main water outlet pipe, a branch water outlet pipe, a main water return pipe and a branch water return pipe when there are 9 battery modules;

[0041] Figures 12a to 12c Schematic diagram of connecting 5, 6 and 7 branch water pipes (branch water outlet pipes and branch water return pipes) through main water pipes (main water outlet pipes and main water return pipes), respectively, and the main water pipes and branch water pipes are connected by right-angle bends;

[0042] Figure 12d to Figure 12f The schematic diagram is that 5, 6 and 7 branch water pipes (branch water outlet pipes and branch water return pipes) are connected through the main water pipe (main water outlet pipe and main water return pipe), and the main water pipe and the branch water pipes are connected by arc bending.

[0043] In the figure: 1, water tank, 10, water outlet of water tank, 11, first water return port of water tank, 12, second water return port of water tank, 2, water pump, 3, pipeline, 30, main water outlet pipe, 31, heat exchange pipe, 32, main water return pipe, 33, branch water outlet pipe, 330, first bending part, 331, first branch water outlet pipe, 332, second branch water outlet pipe, 34, branch return pipe, 340, second bending part, 341, first branch return pipe, 342, second branch return pipe, 35, vortex wing, 350, first spoiler, 351, second spoiler, 36, flow control valve, 37, temperature sensor, 4, battery module, 50, three-way valve I, 51, three-way valve II, 52 three-way joint, 60, compressor, 61, condenser, 62, drying filter, 63, expansion valve, 64, evaporator. DETAILED DESCRIPTION

[0044] Example 1

[0045] like Figure 1 The power battery cooling structure disclosed in the present invention is shown, including a water tank 1, a water pump 2 and a pipeline 3. A heat-conducting medium is placed in the water tank 1. The water tank 1 is provided with a water outlet 10 and a first water return port 11. The pipeline 3 is fixed on the battery module, and one end of the pipeline is connected to the water outlet 10 of the water tank through the water pump 2, and the other end is connected to the first water return port 11 of the water tank. The cross-sectional area of ​​the inner diameter of the pipeline gradually decreases from one end connected to the water outlet of the water tank to the other end.

[0046] Specifically, Figure 1 As shown, the water tank is connected to the refrigeration system of the air conditioning system in the car, and the refrigeration system includes a compressor 60, a condenser 61, a dry filter 62, an expansion valve 63 and an evaporator 64; the compressor 60, the dry filter 62 and the expansion valve 63 are arranged between the condenser 61 and the evaporator 64, and the air conditioning refrigerant can circulate between the evaporator 64, the dry filter 62, the expansion valve 63 and the condenser 61 under the action of the compressor 60, and is cooled through the process of compression, condensation, expansion and evaporation. The water tank 1 is connected to the evaporator 64 through the pipeline 3, and the evaporator The device 64 can cool the heat-conducting medium in the water tank 1. The heat-conducting medium can be water, alcohol or oil. The water tank 1 is provided with a water outlet 10 and a first water return port 11. The pipeline is fixed on the battery module, and one end is connected to the water outlet of the water tank through the water pump 2, and the other end is connected to the first water return port of the water tank. The water pump can drive the heat-conducting medium to flow in the water tank and the pipeline, and then dissipate the heat of the battery module through the pipeline. The cross-sectional area of ​​the inner diameter of the pipeline gradually decreases from one end connected to the water outlet of the water tank to the other end.

[0047] As an improvement of the present invention, the cross-sectional area of ​​the pipeline for circulating the heat-conducting medium gradually decreases from one end connected to the water outlet of the water tank to the other end. When the air conditioner cools the power battery, the cooling medium starts from the wide end of the water tank and flows through increasingly thin pipes. This process is a gradual contraction process of the fluid. According to the principles of fluid mechanics and thermodynamics, the fluid flows through the thicker and thinner pipes, and the coolant will further cool down to achieve a better cooling function. The specific principle is as follows:

[0048]

[0049] For subsonic flow, M<1, (1-M2) / kM2>0, (1-M2) / (k-1)M2>0 (in the formula, k represents the specific heat ratio; M represents the Mach number; T is the temperature of the heat transfer medium, and A is the cross-sectional area of ​​the pipeline). The two sides of the equal sign of the formula have the same sign, that is, the direction of change of the static pressure and temperature of the fluid is the same as the direction of change of the pipeline cross section. Therefore, as the pipeline cross section decreases, the static pressure and temperature of the fluid will decrease. That is to say, when the subsonic fluid flows through the contracting pipeline, its flow rate gradually increases, and the static pressure and temperature gradually decrease, which improves the cooling effect of the pipeline on the battery module.

[0050] Furthermore, if Figure 1 and Figure 2The pipeline 3 shown includes a main water outlet pipe 30, a heat exchange pipe 31 and a main water return pipe 32; the heat exchange pipe 31 includes a heat exchange pipe I 310 and a heat exchange pipe II 311 arranged side by side; one end of the main water outlet pipe 30 is connected to the water outlet 10 of the water tank, and the other end is connected to the water inlet ends of the heat exchange pipe I 310 and the heat exchange pipe II 311; one end of the main water return pipe 32 is connected to the first water return port 11 of the water tank, and the other end is connected to the water outlet ends of the heat exchange pipe I 310 and the heat exchange pipe II 311; the heat exchange pipe is fixed on the battery module, and the flow directions of the heat transfer medium in the heat exchange pipe I and the heat exchange pipe II are opposite. Specifically, in this embodiment, Figure 3 The figure shows the first form of fixing the heat exchange tube on the battery module. The heat exchange tube I 310 and the heat exchange tube II 311 are arranged side by side and fixed on the surface (side wall surface and upper surface) of the battery module. The heat exchange tube I 310 and the heat exchange tube II 311 are arranged side by side and extend from one end of the upper surface to the other end in a serpentine shape, and then are wound on the side wall from the upper part to the lower part. The flow direction of the heat transfer medium in the heat exchange tube I 310 and the heat exchange tube II 311 is as follows: In the heat exchange tube I, the heat transfer medium flows from the upper surface of the battery module to the lower surface of the battery module. It flows in from one end and gradually flows to the other end of the upper surface, then spirals from the upper end of the side wall surface of the battery module to the lower part, and finally flows out from the lower part of the battery module (the water flow direction shown by arrow 2 in the figure). In heat exchange tube II, the heat transfer medium flows in from the lower part of the battery module, then spirals from the lower end to the upper end along the side wall of the battery module, and flows from one end of the upper surface to the other end on the upper surface of the battery module, and finally flows out from the other end of the upper surface (the water flow direction shown by arrow 1 in the figure).

[0051] Figure 4This is the second form of heat exchange tubes arranged on the battery module. The figure only shows the form of arrangement on the upper surface, and the part on the side wall is the same as the first form. The second form is that heat exchange tube I 310 and heat exchange tube II 311 spiral from the center of the upper surface to the edge. In this form, the flow direction of the heat transfer medium is as follows: in heat exchange tube I, the heat transfer medium flows in from the center of the upper surface of the battery module, and gradually flows to the edge of the upper surface, and then spirals from the upper end of the side wall surface of the battery module to the lower part, and finally flows out from the lower part of the battery module (the water flow direction shown by arrow 2 in the figure). In heat exchange tube II, the heat transfer medium flows in from the lower part of the battery module, and then spirals along the side wall of the battery module from the lower end to the upper end, and flows from the edge of the upper surface to the center on the upper surface of the battery module, and finally flows out from the center of the upper surface (the water flow direction shown by arrow 1 in the figure). Heat exchange tube I and heat exchange tube II are arranged side by side and alternately wound on the battery module, that is, the heat transfer medium flows in opposite directions to the cooling water flow in adjacent flow channels. The reverse laminar water flow can improve the temperature consistency at different positions of the heat exchange tube, reduce the temperature difference between the highest temperature and the maximum temperature of the battery pack, and ensure the temperature consistency inside the battery module.

[0052] Furthermore, if Figure 5a , Figure 5b and Figure 5c As shown, the inner wall of the heat exchange tube I 310 and the heat exchange tube II 311 is provided with a raised vortex wing 35. The vortex wing 35 includes a first spoiler 350 and a second spoiler 351 connected to each other. The angle formed at the connection between the first spoiler 350 and the second spoiler 351 is not greater than 90°, and the sharp angle formed by the first spoiler 350 and the second spoiler 351 is consistent with the direction in which the cross-sectional area of ​​the inner diameter of the pipeline decreases. The vortex wing 35 is provided in the heat exchange tube I 310 and the heat exchange tube II 311. The vortex wing 35 can increase the disturbance of the guide medium in the pipeline, thereby allowing the guide medium to fully exchange heat with the pipeline, thereby improving the heat exchange effect of the pipeline.

[0053] Furthermore, the heat exchange tube I 310 and the heat exchange tube II 311 are flat tubes, the flat surface of one side of the flat tube is fixed on the surface of the battery module, and the vortex wing is arranged on the inner wall of the two flat surfaces of the flat tube. The vortex wing is arranged on the two flat surfaces to further increase the disturbance of the flow-guiding medium and improve the heat exchange effect. Preferably, multiple groups of vortex wings are arranged along the length direction of the pipeline, and each group is one or more vortex wings arranged along the width direction of the pipeline, which can obtain a better heat exchange effect.

[0054] Furthermore, aluminum oxide nanoparticles are provided in the heat-conducting medium, and the presence of aluminum oxide nanoparticles can enhance the heat conduction effect of the heat-conducting medium. Specifically, aluminum oxide carbon nanoparticles are provided in the heat-conducting medium, and the thermal conductivity of aluminum oxide nanoparticles is often hundreds or thousands of times that of the heat-conducting medium. The addition of aluminum oxide carbon nanoparticles changes the structure of the original base liquid, and the thermal conductivity of solid nanoparticles is much greater than that of the base liquid, which enhances the heat transfer process inside the nanofluid and improves its thermal conductivity. At the same time, due to the action of Brownian force, van der Waals force, bombardment of surrounding liquid molecules and other forces, the nanoparticles in the aluminum oxide carbon nanofluid are constantly performing irregular micro-movements. This micro-movement causes micro-convection to exist between the nanoparticles and the liquid, thereby enhancing the thermal convection or heat transfer process between the nanoparticles and the liquid, and improving its thermal conductivity. When the nanofluid is used as a car coolant, its thermal conductivity can be increased by up to 53.81%.

[0055] Furthermore, the battery module 4 has a plurality of battery modules, each of which is respectively fixed with a group of heat exchange tubes, the main water outlet pipe 30 is connected to the heat exchange tube through a plurality of branch water outlet pipes 33; the main water return pipe 32 is connected to the heat exchange tube through a plurality of branch water return pipes 34; the branch water outlet pipes 33 are each provided with a temperature control flowmeter 36, and the branch water return pipes 34 are each provided with a temperature sensor 37, the temperature sensor 37 can measure the temperature of each battery module (the temperature of the heat-conducting medium after heat exchange with the battery module), and adjust the temperature control flowmeter to control the flow of the heat-conducting medium flowing into each battery module, thereby making the temperature of each battery module consistent. For each battery module in the battery pack, the temperature is not completely consistent. This is because the battery cells inside each battery module cannot be completely identical during manufacturing. The battery cell monomers are welded, clamped, connected in series and parallel, and connected together to form a module. Inconsistent processes during the processing will lead to inconsistencies between modules. The most intuitive representation is the internal resistance of the module. If the internal resistance is different, the heat generation must be different, so the temperature of each battery module is different. Therefore, cooling the battery pack is not only to reduce the overall temperature, but also to ensure that the temperature difference of each battery module is small, so as to ensure that the temperature of multiple battery modules is consistent, which is more conducive to the working efficiency of the battery pack.

[0056] Furthermore, if Figure 6 As shown, one end of the branch water outlet pipe 33 is a first bend 330, and the first bend 330 is connected to the main water outlet pipe 30. One end of the branch water return pipe 34 is a second bend 340, and the second bend 340 is connected to the main water return pipe 32. The branch water pipe is connected to the main water pipe by setting a bend, which reduces the energy loss of the heat transfer medium and improves the heat exchange efficiency.

[0057] Furthermore, the number of the battery modules is more than 8, the outlet water pipe 33 includes a primary outlet water pipe 331 and a secondary outlet water pipe 332, and the number of the primary outlet water pipe 331 is an odd number; the return water pipe 34 includes a primary return water pipe 341 and a secondary return water pipe 342, and the number of the primary return water pipe 341 is an odd number. Fig.10 As shown, in this embodiment, the number of battery modules is 8, the main water outlet pipe 30 is connected to an odd number of first-level branch water outlet pipes 331 (3 in the figure), and each first-level branch water outlet pipe 331 is connected to the heat exchange tube through a second-level branch water outlet pipe 332, and the number of second-level branch water outlet pipes connected to each first-level branch water outlet pipe 331 is also as odd as possible (the number of second-level branch water outlet pipes connected to the three first-level branch water outlet pipes in the figure is 3, 3, and 2 respectively). Similarly, the number of first-level return water pipes 341 is also an odd number (3 in the figure), and the number of second-level return water pipes connected to each first-level return water pipe 331 is also as odd as possible (the number of second-level return water pipes connected to the three first-level return water pipes in the figure is 3, 3, and 2 respectively). Fig.11 As shown, in another embodiment of the present invention, the number of battery modules is 9, the main water outlet pipe 30 is connected to an odd number of first-level branch water outlet pipes 331 (3 in the figure), each first-level branch water outlet pipe 331 is connected to the heat exchange tube through a second-level branch water outlet pipe 332, and the number of second-level branch water outlet pipes connected to each first-level branch water outlet pipe 331 is also as odd as possible (the number of second-level branch water outlet pipes connected to the three first-level branch water outlet pipes in the figure is 3, 3 and 3 respectively), similarly, the number of first-level return water pipes 341 is also an odd number (3 in the figure), and the number of second-level branch return water pipes connected to each first-level branch return water pipe 331 is also as odd as possible (the number of second-level branch return water pipes connected to the three first-level branch return water pipes in the figure is 3, 3 and 3 respectively).

[0058] One end of the outlet pipe is the first bend, and one end of the return pipe is the second bend, that is, both ends of the heat exchange pipe adopt a streamlined design, which reduces the flow resistance of the heat transfer medium outside the battery pack (the part outside the heat exchange pipe, that is, the part that does not directly exchange heat with the battery pack), thereby reducing heat loss. Experiments have shown that the streamlined design maximizes the efficiency of the heat exchanger, which may be as high as 44.52%. The principle is as follows: j*f is a dimensionless factor. In the heat exchange of plate structures, this dimensionless factor is widely used to evaluate the quality of heat transfer. j is a dimensionless parameter that represents the heat transfer effect of the surface. The specific formula is shown in (2), where Nu is the Nusselt number, Re is the Reynolds number, and Pr is the Prandtl number.

[0059]

[0060] f is the friction coefficient of the inner surface of the flow channel; this coefficient is calculated by the following formula:

[0061]

[0062] Among them, D0 is the hydraulic diameter inside the flow channel; ΔP is the difference between the pressure at the outlet and the inlet of the pipeline, which we call pressure drop; L1 represents the length of the fluid flowing in the pipeline; G represents the mass flow rate; ρ is the density. After using HYPERMESH14.0 to model the pipeline, it was analyzed in ANSYS FLUENT 17.0. In the simulation, three channel modes 5, 6, and 7 were set, such as Figures 12a to 12f As shown, the channels are divided into streamlined and conventional right-angle bending structures. The simulation results show that non-streamlined channels are prone to produce eddies and turbulence in the right-angle area, increase flow resistance, and have an adverse effect on the cooling effect. By adopting streamlined channels, the probability of eddies and turbulence can be effectively reduced. In addition, by comparing the flow velocities in the pipelines of the odd-numbered channel model and the even-numbered channel model, it is found that the flow velocity in the middle channel is much higher than the fluid flow velocity in the channels on both sides. The difference in streamline velocity of the odd-numbered channels is significantly smaller than that of the even-numbered channels, so the odd-numbered channels are conducive to the stable flow of the entire fluid. When setting the number of pipelines in the design, the principle of odd-numbered pipelines is adopted. That is, the j*f proportional factor above also shows the same effect. In the above analysis, the proportional factor is the highest for the streamlined design pipeline with 7 channels.

[0063] Example 2

[0064] like Figure 7 As shown, the second structure of the power battery cooling structure disclosed in the present invention includes a water tank 1, a water pump 2, a pipeline 3, a three-way valve I50, a three-way valve II51 and a three-way joint 52. The water tank is provided with a heat-conducting medium. The water tank 1 is provided with a water outlet 10, a first water return port 11 and a second water return port 12. The first interface of the three-way valve I50 is connected to the water outlet 10 of the water tank, and the second interface is connected to the water inlet end of the water pump 2; the first interface of the three-way valve II51 is connected to the water outlet end of the water pump 2 The second interface is connected to the second water return port 12 of the water tank, and the third interface is connected to the first interface of the three-way joint 52; the second interface of the three-way joint 52 is connected to the pipeline 3, and the third interface is connected to the third interface of the three-way valve Ⅰ50. The pipeline is fixed on the battery module, and one end is connected to the water outlet of the water tank through the water pump, and the other end is connected to the first water return port of the water tank. The cross-sectional area of ​​the inner diameter of the pipeline gradually decreases from one end connected to the water outlet of the water tank to the other end.

[0065] Specifically, Figure 7As shown, the water tank is connected to the refrigeration system of the air-conditioning system in the car, and the refrigeration system includes a compressor, a condenser, a drying filter, an expansion valve and an evaporator; the compressor, the drying filter and the expansion valve are arranged between the condenser and the evaporator, and the air-conditioning refrigerant can circulate between the evaporator, the drying filter, the expansion valve and the evaporator under the action of the compressor, and is cooled through the compression, condensation, expansion and evaporation processes. The evaporator can heat the refrigerant in the refrigeration system, and the water tank is connected to the refrigeration system through a water pipe. Three-way valves are respectively provided on the two water pipes (water inlet pipe and water return pipe) connecting the water tank and the refrigeration system. The two three-way valves can realize the connection between the water tank and the evaporator or the connection between the water tank and the condenser. When the water tank is connected to the evaporator, the refrigeration system can cool down (cool) the heat-conducting medium in the water tank, and when the water tank is connected to the condenser, the refrigeration system can heat up (heat) the heat-conducting medium in the water tank. The heat-conducting medium can be water, alcohol, oil or other media. The water tank is provided with a water outlet and a first water return port. The pipeline is fixed on the battery module, and one end is connected to the water outlet of the water tank through the water pump, and the other end is connected to the first water return port of the water tank. The water pump can drive the heat-conducting medium to flow in the water tank and the pipeline, and then dissipate the heat of the battery module through the pipeline. The cross-sectional area of ​​the inner diameter of the pipeline gradually decreases from one end connected to the water outlet of the water tank to the other end.

[0066] Specifically, when the battery module needs to be cooled, Figure 8 As shown, the water tank is connected to the evaporator, the evaporator cools down the heat-conducting medium in the water tank, the three-way valve I connects the water tank and the water pump (that is, the first interface and the second interface of the three-way valve I are connected), the three-way valve II connects the water pump and the three-way joint (that is, the first interface and the third interface of the three-way valve II are connected), and the heat-conducting medium flows through the three-way valve I, the water pump, the three-way valve II, the three-way joint and the pipeline once, and returns to the water tank after cooling the battery module through the pipeline.

[0067] When the battery module needs to be heated, Fig. 9 As shown, the water tank is connected to the condenser, the condenser heats the heat transfer medium in the water tank, the three-way valve I is connected to the water pump and the three-way joint (that is, the second interface and the third interface of the three-way valve I are connected), the three-way valve II is connected to the water pump and the water tank (that is, the first interface and the second interface of the three-way valve II are connected), and the heat transfer medium flows through the pipeline, the three-way joint, the three-way valve I, the water pump and the three-way valve II once and then flows back to the water tank, and heats the battery module through the pipeline. This structure can realize both cooling and heating of the battery module, simplifying the structure, and at the same time, ensuring that the battery module works within a suitable temperature range.

[0068] At the same time, as an improvement of the present invention, the cross-sectional area of ​​the pipeline for circulating the heat-conducting medium gradually decreases from one end connected to the water outlet of the water tank to the other end. When the air conditioner cools the power battery, the cooling medium starts from the wide end of the water tank and flows through increasingly thin pipes. This process is a gradual contraction process of the fluid. According to the principles of fluid mechanics and thermodynamics, the fluid flows through the thick and thin pipes, and the coolant will further cool down to achieve a better cooling function. The specific principles are as follows:

[0069]

[0070] For subsonic flow, M<1, (1-M2) / kM2>0, (1-M2) / (k-1)M2>0 (in the formula, k represents the specific heat ratio; M represents the Mach number; T is the temperature of the heat transfer medium, and A is the cross-sectional area of ​​the pipeline). The two sides of the equal sign of the formula have the same sign, that is, the direction of change of the static pressure and temperature of the fluid is the same as the direction of change of the pipeline cross section. Therefore, as the pipeline cross section decreases, the static pressure and temperature of the fluid will decrease. That is to say, when the subsonic fluid flows through the contracting pipeline, its flow rate gradually increases, and the static pressure and temperature gradually decrease, which improves the cooling effect of the pipeline on the battery module.

[0071] When the air conditioner heats the power battery (the outside temperature is low, and the battery module needs to be heated to make it work within an appropriate temperature range), the heat transfer medium starts from the narrow end of the water tank and flows through increasingly thicker pipes. This process is the gradual expansion of the fluid. According to the principles of fluid mechanics and thermodynamics, the fluid flows through the pipes that become thinner and thicker, and the heat transfer medium will further heat up, thereby realizing the function of heating the battery pack, which can reduce the energy consumption of the car's air-conditioning system.

[0072] Further, the pipeline includes a main water outlet pipe, a heat exchange pipe and a main water return pipe; the heat exchange pipe includes a heat exchange pipe I and a heat exchange pipe II arranged side by side; one end of the main water outlet pipe is connected to the water outlet of the water tank, and the other end is connected to the water inlet of the heat exchange pipe I and the heat exchange pipe II; one end of the main water return pipe is connected to the first water return port of the water tank, and the other end is connected to the water outlet of the heat exchange pipe I and the heat exchange pipe II; the heat exchange pipe is fixed on the battery module, and the flow direction of the heat transfer medium in the heat exchange pipe I and the heat exchange pipe II is opposite. This structure is the same as that in Example 1 and will not be described in detail.

[0073] Furthermore, the inner walls of the heat exchange tubes I and II are provided with raised vortex wings, and the heat transfer medium is provided with aluminum oxide nanoparticles. The specific structure and arrangement of the vortex wings are the same as those in Example 1 and will not be described in detail.

[0074] Furthermore, there are a plurality of battery modules, each of which is respectively fixed with a group of heat exchange tubes, and the main water outlet pipe is connected to the heat exchange tubes through a plurality of branch water outlet pipes;

[0075] The main water return pipe is connected to the heat exchange pipe via a plurality of branch water return pipes;

[0076] The outlet water pipes are provided with temperature control flow meters, and the return water pipes are provided with temperature sensors. The structure is the same as that in Example 1, and will not be described repeatedly.

[0077] Furthermore, the number of the battery modules is more than 8, the branch water pipes include a primary branch water pipe and a secondary branch water pipe, and the number of the primary branch water pipes is an odd number;

[0078] The branch return pipe includes a primary branch return pipe and a secondary branch return pipe, and the number of the primary branch return pipes is an odd number. One end of the branch outlet pipe is a first curved portion, which is connected to the main outlet pipe, and one end of the branch return pipe is a second curved portion, which is connected to the main return pipe. This part of the structure is also the same as that in Example 1, and will not be described repeatedly.

[0079] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A power battery cooling structure, comprising a water tank (1), a water pump (2) and a pipeline (3), wherein a heat-conducting medium is placed in the water tank (1), the water tank (1) is provided with a water outlet (10) and a first water return port (11), the pipeline (3) is fixed to a battery module (4), and one end of the pipeline is connected to the water outlet (10) of the water tank through the water pump (2), and the other end is connected to the first water return port (11) of the water tank, characterized in that: The cross-sectional area of ​​the inner diameter of the pipeline (3) gradually decreases from one end connected to the water outlet of the water tank to the other end; The pipeline (3) comprises a main water outlet pipe (30), a heat exchange pipe (31) and a main water return pipe (32); The heat exchange tube (31) comprises a heat exchange tube I (310) and a heat exchange tube II (311) arranged side by side; One end of the main water outlet pipe (30) is connected to the water outlet (10) of the water tank, and the other end is connected to the water inlet ends of the heat exchange tube I (310) and the heat exchange tube II (311); One end of the main water return pipe (32) is connected to the first water return port (11) of the water tank, and the other end is connected to the water outlet ends of the heat exchange tube I (310) and the heat exchange tube II (311); The heat exchange tube (31) is fixed on the battery module, and the flow directions of the heat transfer medium in the heat exchange tube I (310) and the heat exchange tube II (311) are opposite; There are multiple battery modules, each of which is respectively fixed with a group of heat exchange tubes, and the main water outlet pipe is connected to the heat exchange tubes through multiple branch water outlet pipes; The main water return pipe is connected to the heat exchange pipe via a plurality of branch water return pipes; The outlet water pipes are provided with temperature control flow meters, and the return water pipes are provided with temperature sensors; The branch water outlet pipe comprises a primary branch water outlet pipe and a secondary branch water outlet pipe, and the number of the primary branch water outlet pipe and the secondary branch water outlet pipe is an odd number; The branch return water pipe includes a primary branch return water pipe and a secondary branch return water pipe, and the number of the primary branch return water pipe and the secondary branch return water pipe is an odd number.

2. The power battery cooling structure according to claim 1, characterized in that: It also includes a three-way valve I (50), a three-way valve II (51) and a three-way joint (52); the water tank (1) is provided with a second water return port (12); The first interface of the three-way valve I (50) is connected to the water outlet (10) of the water tank, and the second interface is connected to the water inlet end of the water pump (2); The first interface of the three-way valve II (51) is connected to the water outlet of the water pump (2), the second interface is connected to the second water return port (12) of the water tank, and the third interface is connected to the first interface of the three-way connector (52); The second interface of the three-way connector (52) is connected to the pipeline (3), and the third interface is connected to the third interface of the three-way valve I (50).

3. The power battery cooling structure according to claim 2, characterized in that: The inner walls of the heat exchange tube I (310) and the heat exchange tube II (311) are provided with protruding vortex wings.

4. The power battery cooling structure according to claim 3, characterized in that: The vortex wing includes a first spoiler and a second spoiler connected to each other, the angle formed at the connection between the first spoiler and the second spoiler is no more than 90°, and the sharp angle formed by the first spoiler and the second spoiler is consistent with the direction in which the cross-sectional area of ​​the inner diameter of the pipeline decreases.

5. The power battery cooling structure according to claim 4, characterized in that: The heat exchange tube I (310) and the heat exchange tube II (311) are flat tubes, a flat surface on one side of the flat tube is fixed on the surface of the battery module, and the vortex wing is arranged on the inner walls of the two flat surfaces of the flat tube.

6. The power battery cooling structure according to claim 5, characterized in that: Aluminum oxide nanoparticles are arranged in the heat conducting medium.

7. The power battery cooling structure according to claim 6, characterized in that: One end of the branch water outlet pipe is a first curved portion, which is connected to the main water outlet pipe; one end of the branch water return pipe is a second curved portion, which is connected to the main water return pipe.

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