Power battery fused salt heating device and heating method thereof

Abstract

The invention relates to the technical field of power battery heating, in particular to a power battery fused salt heating device. A power battery fused salt heating device comprises a heat storage tank, a heating unit, a heat exchange unit and a water pump, a heat storage medium is stored in the heat storage tank, the heating unit and the heat exchange unit are both arranged in the heat storage tank, the heating unit is used for heating the heat storage medium, and the heat exchange unit is used for heating the heat storage medium. The heat exchange unit is used for exchanging heat of a heat storage medium with the outside, the water pump is arranged outside the heat storage tank and connected with the heat exchange unit, and the water pump is used for pumping a heat exchange medium to the heat exchange unit. According to the power battery fused salt heating device, the heat storage tank is used for storing heat to heat the power battery, the electric quantity of the power battery is not consumed, the heat stored by the fused salt serves as a heat source, the heat exchange medium transfers the heat to heat the power battery after heat exchange, the working temperature of the power battery is increased, and the chemical performance and the endurance mileage of the power battery are maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery heating, and in particular to a power battery molten salt heating device and a heating method thereof. Background Art

[0002] In low temperature environments, power batteries have problems such as reduced chemical properties, poor charging and discharging performance, and short cruising range, which affect the normal use of electric vehicles. In order to meet the requirements of usability and safety of electric vehicles in low temperature environments, it is particularly important to take heating measures for power batteries.

[0003] At present, the heating methods of electric vehicle power batteries are mainly divided into internal heating and external heating. Internal heating is to heat the power battery by charging alternating current into the positive and negative electrodes of the battery. The temperature rise rate of internal heating is relatively fast, but it has a certain impact on the battery life and safety. External heating is mainly heated by positive temperature coefficient thermistor (PTC, Positive Temperature Coefficient) heating, battery membrane heating and other electric heating elements. Electric heating element heating is the fastest heating and the simplest way to control the battery temperature difference in external heating, but it is mostly provided by the power battery itself, consuming the energy of the power system.

[0004] Many domestic scholars have carried out a series of designs for power battery heating devices. The invention patent with authorization number ZL111355003B, "A heating method for a power battery heating device", proposes a device that uses a supercapacitor to connect to a heating film to generate heat and an external heating device to jointly heat the power battery. This heating device requires an accurate judgment mechanism to switch different combined heating methods, which is relatively complicated; the invention patent with application number 202410032210.2, "A power battery heating device and a method for thermal management control", discloses a heating device with heating wires arranged on the basis of a liquid thermal component. When the heating wires of this device are connected in series, if any heating wire fails, the device is at risk of failure; the invention patent with application number 202210882901.2, "A power battery heating device and its heating control method", proposes a device that uses a drive motor to generate heat to heat a power battery. The drive motor of this device generates little heat in a low-temperature environment and requires the intervention of multiple drive motors, which has a certain impact on the power system of electric vehicles. Summary of the invention

[0005] In order to remedy the defects of the prior art, the present invention provides a power battery molten salt heating device and a heating method thereof, so that the power battery can be heated to a suitable operating temperature when working in a low temperature environment, thereby maintaining the chemical properties of the power battery and improving the cruising range.

[0006] To achieve the above-mentioned purpose, a power battery molten salt heating device comprises a heat storage tank, a heating unit, a heat exchange unit and a water pump, wherein a heat storage medium is stored in the heat storage tank, and the heating unit and the heat exchange unit are both arranged in the heat storage tank, wherein the heating unit is used to heat the heat storage medium, and the heat exchange unit is used to exchange the heat of the heat storage medium with the outside world, and the water pump is arranged outside the heat storage tank and connected to the heat exchange unit, and the water pump is used to pump the heat exchange medium to the heat exchange unit.

[0007] Furthermore, a flange is provided at one end of the heat storage tank, and a water pump interface, a feed port, a heating unit installation channel and a heat exchange unit installation channel are integrated on the flange, wherein the water pump interface is connected to the water inlet of the water pump, and the feed port is used to add heat storage medium.

[0008] Furthermore, the heating unit is a heater, the heater passes through the heating unit installation channel and is horizontally placed in the heat storage tank, and a sleeve is provided on the outside of the heater.

[0009] Furthermore, the heat exchange unit is a heat exchanger, which is installed in the heat storage tank through the heat exchange unit installation channel. The heat exchanger has a water inlet and a water outlet. The water inlet of the heat exchanger is connected to the water pump, and the water outlet of the heat exchanger is connected to the power battery.

[0010] Furthermore, the heat exchanger is a spiral tube heat exchanger.

[0011] Furthermore, the heat storage medium is one of HTS ternary molten salt, Hetic XL ternary molten salt, and Solar Salt binary molten salt.

[0012] Furthermore, the heat exchange medium is one of ethylene glycol solution, heat transfer oil and antifreeze liquid.

[0013] Furthermore, the inner wall of the heat storage tank is a nickel layer, and the outer wall is provided with an insulating layer; and a support seat is provided at the bottom of the heat storage tank.

[0014] A power battery system comprises a power battery, a water tank and the above-mentioned heating device, wherein the water tank stores a heat exchange medium, and the water outlet of the water tank is connected to the water pump interface through a pipeline, and the power battery is connected to the heat exchange unit.

[0015] A method for heating molten salt of a power battery is implemented by using the above-mentioned heating device, and specifically comprises the following steps:

[0016] S1, start the heating unit to heat the heat storage medium. After the temperature in the heat storage tank reaches the rated temperature, turn off the heating unit to achieve heat storage;

[0017] S2. When the temperature of the power battery is lower than the preset operating temperature, the water pump is started to pump the heat exchange medium to the heat exchange unit. The heat exchange medium circulates between the heat exchange unit and the power battery to transfer the heat in the heat storage tank to the power battery, thereby realizing heat exchange and heating the power battery.

[0018] S3. After the thermal energy stored in the heat storage tank is consumed, the water pump is turned off and the heat transport of the heat storage tank stops.

[0019] The beneficial effects of the present invention are as follows: the power battery molten salt heating device of the present invention adopts a heat storage tank to store heat to achieve heating of the power battery, does not consume the power of the power battery, uses the heat stored in the molten salt as a heat source, and the heat exchange medium transfers heat to heat the power battery after heat exchange, thereby increasing the working temperature of the power battery and maintaining the chemical properties and cruising range of the power battery; the molten salt has a large energy storage density and a low melting point, and can be used as both a heat storage medium and a heat release medium, and can be recycled, effectively saving material costs and having a high energy utilization rate; the heat storage tank is a single-tank horizontal arrangement, the molten salt is stored in the heat storage tank, and heat exchange is achieved by the heat exchange medium flowing in the heat exchanger, which effectively prevents the molten salt from solidifying and clogging when flowing in the heat exchanger, and the device integrates heat storage, heat release and heat exchange, has a simple structure, and is easy to process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a molten salt heating device for a power battery of the present invention;

[0021] Figure 2 It is a structural schematic diagram of a molten salt heating device for a power battery.

[0022] In the figure: 1-water pump interface; 2-feed port; 3-heat exchange unit installation channel; 4-heating unit installation channel; 5-flange; 6-heat storage tank; 7-water pump; 8-heat exchange unit; 9-heating unit. Specific implementation plan

[0023] The following part further describes the present invention in conjunction with the accompanying drawings and specific implementation methods, but does not limit the scope of protection thereof.

[0024] like Figure 1-2 A power battery molten salt heating device comprises a heat storage tank 6, a heating unit 9 and a heat exchange unit 8, wherein the heat storage tank 6 stores a heat storage medium, and the heating unit 9 and the heat exchange unit 8 are both arranged in the heat storage tank 6, wherein the heating unit 9 is used to heat the heat storage medium, and the heat exchange unit 8 is used to exchange the heat of the heat storage medium with the outside world.

[0025] In the present invention, the heat storage tank 6 is a single tank horizontal structure, one end of which is elliptical and closed, and the other end is a feeding end. In order to ensure the thermal insulation performance of the heat storage tank 6, the heat storage tank 6 is made of 316L stainless steel-Ni composite material, the inner wall of which is a nickel layer, and the outer wall of the heat storage tank 6 is an insulating layer, and the thermal conductivity of the material used for the insulating layer is not higher than 0.07W / (m·k). As an embodiment of the insulating layer of the present invention, the insulating layer located at the bottom of the outer wall of the heat storage tank 6 is made of foam glass, and the insulating layer of the rest of the heat storage tank 6 includes a mineral wool layer and a calcium silicate layer, and the mineral wool layer and the calcium silicate layer are alternately arranged. A support seat 10 is provided at the bottom of the heat storage tank 6 to facilitate the transportation of the heat storage tank 6.

[0026] In the present invention, the heat storage medium is one of HTS (53% KNO3-7% NaNO3-40% NaNO2) ternary molten salt, Hetic XL (45% KNO3-7% NaNO3-48% Ca(NO3)2) ternary molten salt, and Solar Salt (60% NaNO3-40% KNO3) binary molten salt. Preferably, the heat storage medium of the present invention is HTS (53% KNO3-7% NaNO3-40% NaNO2) ternary molten salt.

[0027] As another embodiment of the present invention, the heating unit 9 is a heater, which is horizontally placed in the heat storage tank 6, and a sleeve is provided on the outside of the heater.

[0028] In the present invention, the heater heats the heat storage medium to store heat to meet the needs of heating the power battery. The heater is preferably provided with a temperature sensor to monitor the temperature in the heat storage tank 6 and automatically shuts down when the set temperature is reached. The casing is filled with air. The casing is provided outside the heater to prevent the heater from being damaged by excessive temperature when in contact with the heat storage medium, and effectively prevents leakage of the heat storage medium when replacing the heater. The heater of the present invention is preferably made of a material that is resistant to high temperatures and molten salt corrosion, such as low-carbon austenitic stainless steel 316L.

[0029] As another embodiment of the present invention, the heat exchange unit 8 is a heat exchanger, which is one of a U-type, a W-type, and a spiral tube type. The heat exchanger is arranged in the heat storage tank 6, and has a water inlet and a water outlet. A water pump 7 is provided at one end of the heat storage tank 6, and the water pump 7 is connected to the water inlet of the heat exchanger. The water pump 7 is used to pump heat exchange medium into the heat exchanger, and the outlet of the heat exchanger is connected to the power battery.

[0030] In the present invention, the heat exchanger is a spiral tube heat exchanger, and its spiral tube is a single-channel spiral tube. One end of the spiral tube heat exchanger extends into the heat storage tank 6, and bends at the end of the spiral to return to one end in the form of a straight tube. The inlet and outlet are located at the same end, arranged at 180 degrees. The spiral tube heat exchanger is immersed in the high-temperature heat storage medium, and heat exchange is achieved through the flow of the heat exchange medium. The spiral tube heat exchanger is made of low-carbon austenitic stainless steel 316L and other materials that are resistant to high temperature and molten salt corrosion. The water pump 7 has an electric valve and a temperature sensor, which can automatically open and close and monitor the temperature of the heat exchange medium, promote the circulation of the fluid outflow and flow back from the heat storage tank 6, and the high-temperature fluid does not directly contact the power battery. The heat is transferred to the power battery through the heat-conducting pipe arranged in the power battery pack to achieve the purpose of heating the power battery. The heat exchange medium is one of ethylene glycol solution, heat transfer oil and antifreeze, which is stored in an external water tank. The best heat storage medium of the present invention is ethylene glycol solution (50%), and the flow rate of 50% ethylene glycol solution at the inlet of the spiral tube heat exchanger is 2m / s. The secondary flow effect of the spiral tube makes the outlet temperature show stratification phenomenon, the highest temperature is 50°C, the lowest temperature is 43°C, and the average temperature of the high-temperature fluid at the outlet of the spiral tube heat exchanger after heat exchange is 46.5°C. There is heat loss during the flow of the heat exchange medium, so the temperature is at a safe temperature and does not exceed the acceptable limit of 60°C for the power battery.

[0031] As an embodiment of the present invention, in order to facilitate the fixation and connection of various components, a flange 5 is provided at one end of the heat storage tank 6, and a water pump interface 1, a heating unit installation channel 4, a heat exchange unit installation channel 3 and a feed port 2 are integrated on the flange 5, wherein the heat exchanger and the water pump 7 are connected through a pipeline passing through the water pump interface 1, the heating unit installation channel 4 is used to install the heater, the heat exchange unit installation channel 3 is used to install the heat exchanger, and the feed port 2 is used to add heat storage medium.

[0032] The power battery molten salt heating device of the present invention adopts a heat storage tank 6 to store heat to achieve heating of the power battery without consuming power of the power battery. The heat stored in the molten salt is used as a heat source, and the heat exchange medium transfers heat to heat the power battery after heat exchange, thereby increasing the working temperature of the power battery and maintaining the chemical properties and cruising range of the power battery. The molten salt has a large energy storage density and a low melting point. It can be used as both a heat storage medium and a heat release medium, and can be recycled, effectively saving material costs and achieving high energy utilization. The heat storage tank 6 is a single-tank horizontal arrangement, and the molten salt is stored in the heat storage tank 6. Heat exchange is achieved by the flow of the heat exchange medium in the heat exchanger, which effectively prevents the molten salt from solidifying and clogging when flowing in the heat exchanger. The device integrates heat storage, heat release and heat exchange, has a simple structure, and is easy to process.

[0033] The second object of the present invention is to protect a power battery system, which includes a power battery, a water tank, a control unit and the above-mentioned heating device. The water tank stores heat exchange medium, and its water outlet is connected to the water pump interface 1 through a pipeline. A liquid level sensor is provided in the water tank, the power battery is connected to the heat exchanger, and the control unit is electrically connected to the water pump 7, the liquid level sensor, the temperature sensor and the electric valve. The control unit is used to realize automatic heating and heat exchange control of the entire device. The best control unit is a PLC or a single-chip microcomputer.

[0034] The power battery system of the present invention utilizes the heat stored in the heating device to heat the power battery, thereby preventing low temperature from damaging the life of the power battery and increasing the service life of the power battery.

[0035] The third object of the present invention is to provide a heating method for a power battery molten salt heating device, which specifically comprises the following steps:

[0036] S1, start the heater to heat the heat storage medium, and after the temperature in the heat storage tank 6 reaches the rated temperature, turn off the heater to achieve heat storage;

[0037] Specifically, the heater is connected to a charging pile or a household power supply to heat the molten salt in the heat storage tank 6 to store heat. When the temperature sensor detects that the temperature in the heat storage tank 6 reaches the set temperature limit, the control unit controls the heater to turn off to achieve heat storage;

[0038] S2. When the temperature of the power battery is lower than the preset operating temperature, the water pump 7 is started, and the water pump 7 pumps the heat exchange medium to the heat exchanger. The heat exchange medium circulates between the heat exchanger and the power battery to transfer the heat in the heat storage tank 6 to the power battery, thereby realizing heat exchange and heating the power battery.

[0039] Specifically, when the temperature sensor detects that the temperature of the power battery reaches the start-up condition of the heating device, the control unit controls the electric valve of the water pump 7 to open, promotes the heat exchange medium to enter the heat exchanger for heat exchange, drives the heat to flow out of the heat storage tank 6, and realizes heat exchange; the high-temperature heat exchange medium is transported through the heat conduction pipeline to transfer heat to the power battery to realize heating, and the low-temperature heat exchange medium re-enters the heat exchanger through the reflux pipeline to continue heat exchange, and the heat exchange medium continuously drives the heat to flow out of the heat storage tank 6 to ensure continuous heating of the power battery;

[0040] S3. When the temperature sensor detects that the temperature of the heat exchange medium at the heat exchanger outlet is lower than the specified temperature, the heat of the heat storage medium in the heat storage tank 6 is consumed, and the control unit controls the electric valve of the water pump 7 to close, waiting for the next round of heat exchange cycle to start.

[0041] Specifically, when the temperature sensor detects that the temperature in the heat storage tank 6 is lower than the specified temperature, the control unit controls the electric valve of the water pump 7 to close, and the heating is completed.

[0042] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A power battery molten salt heating device, characterized in that: The invention comprises a heat storage tank, a heating unit, a heat exchange unit and a water pump, wherein the heat storage tank stores a heat storage medium, the heating unit and the heat exchange unit are both arranged in the heat storage tank, wherein the heating unit is used to heat the heat storage medium, the heat exchange unit is used to exchange the heat of the heat storage medium with the outside, the water pump is arranged outside the heat storage tank, connected to the heat exchange unit, and the water pump is used to pump the heat exchange medium to the heat exchange unit.

2. A power battery molten salt heating device according to claim 1, characterized in that: A flange is provided at one end of the heat storage tank, and a water pump interface, a feed port, a heating unit installation channel and a heat exchange unit installation channel are integrated on the flange, wherein the water pump interface is connected to the water inlet of the water pump, and the feed port is used to add heat storage medium.

3. A power battery molten salt heating device according to claim 2, characterized in that: The heating unit is a heater, which passes through the heating unit installation channel and is horizontally placed in the heat storage tank. A sleeve is provided on the outside of the heater.

4. A power battery molten salt heating device according to claim 2, characterized in that: The heat exchange unit is a heat exchanger, which is installed in the heat storage tank through the heat exchange unit installation channel. The heat exchanger has a water inlet and a water outlet. The water inlet of the heat exchanger is connected to the water pump, and the water outlet of the heat exchanger is connected to the power battery.

5. A power battery molten salt heating device according to claim 4, characterized in that: The heat exchanger is a spiral tube heat exchanger.

6. A power battery molten salt heating device according to claim 1, characterized in that: The heat storage medium is one of HTS ternary molten salt, Hetic XL ternary molten salt, and Solar Salt binary molten salt.

7. A power battery molten salt heating device according to claim 1, characterized in that: The heat exchange medium is one of ethylene glycol solution, heat transfer oil and antifreeze solution.

8. A power battery molten salt heating device according to claim 1, characterized in that: The inner wall of the heat storage tank is a nickel layer, and the outer wall is provided with an insulating layer; the bottom of the heat storage tank is provided with a support seat.

9. A power battery system, characterized in that: It comprises a power battery, a water tank and the heating device according to any one of claims 1 to 8, wherein the water tank stores a heat exchange medium, and a water outlet thereof is connected to the water pump interface through a pipeline, and the power battery is connected to the heat exchange unit.

10. A method for heating molten salt of a power battery, characterized in that: The method is performed by using the heating device according to any one of claims 1 to 8, and specifically comprises the following steps: S1, start the heating unit to heat the heat storage medium. After the temperature in the heat storage tank reaches the rated temperature, turn off the heating unit to achieve heat storage; S2. When the temperature of the power battery is lower than the preset operating temperature, the water pump is started to pump the heat exchange medium to the heat exchange unit. The heat exchange medium circulates between the heat exchange unit and the power battery to transfer the heat in the heat storage tank to the power battery, thereby realizing heat exchange and heating the power battery. S3. After the thermal energy stored in the heat storage tank is consumed, the water pump is turned off and the heat transport of the heat storage tank stops.

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