A compact heat storage device for vehicle with controllable heat transfer across temperature zones

Abstract

The application provides a compact heat storage device for vehicles with cross-temperature-zone controllable heat transfer, which comprises a heat storage tank, a liquid storage tank and a heat exchange pipe, the heat storage tank comprises a heat storage tank body and a heat storage tank end cover, the liquid storage tank comprises a liquid storage tank body, the liquid storage tank body is a storage chamber for storing liquid metal, the heat exchange pipe passes through the center axis of the storage chamber in sequence from the heat storage tank body, a vacuum layer one, a heat storage layer, an electric heating layer, a high-temperature heat insulation layer and a vacuum layer two are sequentially arranged in the heat storage tank body outside the heat exchange pipe, and the vacuum layer one is communicated with the storage chamber through a gas extraction hole. During charging, electric energy is converted into heat energy and stored. During heat release, the heat release power is adjusted by controlling the height of the liquid metal filled in the vacuum layer, on one hand, boiling of the cooling liquid can be prevented, so that the cooling liquid can be directly introduced into the device to complete high-power heat extraction, on the other hand, the heat exchange area can be increased in time when the heat storage capacity of the device decreases to maintain the heat release power of the device.

Description

Technical Field

[0001] This invention relates to the field of electric thermal energy storage technology, specifically to a compact automotive thermal energy storage device with controllable heat transfer across temperature zones. Background Technology

[0002] Medium- and high-temperature metal phase change materials (PCMs) possess both high heat storage density and high thermal conductivity. Among them, aluminum-silicon alloys also exhibit high latent heat of phase change and relatively low corrosivity, making them the most widely researched and applied metal PCM storage materials. PCM storage devices typically involve melting the metal material and storing it in a corrosion-resistant container to form a storage tank. Electric heating devices and heat exchange pipes are in contact with the metal material for heat charging and extraction. PCM storage devices can be used for renewable energy power consumption and regulation, retrofitting traditional thermal power plants, solar thermal power generation, high-end residential and commercial building heat storage and heating / hot water supply, and heat storage in electric cars and buses for winter cabin heating and battery insulation.

[0003] Because the phase transition temperature of metallic phase change materials is generally high, in many applications, such as winter heating for electric vehicles, the heat storage temperature is much higher than the heat usage temperature. High temperatures in heat storage can effectively increase heat storage density, thereby increasing the power of the heat storage device. However, due to the excessively high temperature, the coolant boils upon entry, making direct heat exchange from inside the device difficult. Using air exchange, on the other hand, would reduce the heat release power. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a compact automotive heat storage device with controllable heat transfer across temperature zones. The high-power heat extraction problem is solved by adding a vacuum layer between the heat storage layer and the heat exchange tubes to prevent the coolant from boiling inside the device, while the heat release power regulation problem is solved by utilizing the filling of liquid metal.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a compact automotive heat storage device with cross-temperature zone controllable heat transfer, comprising a heat storage tank, a liquid storage tank, and a heat exchange pipe. The heat storage tank includes a heat storage tank body and a heat storage tank end cap. The liquid storage tank includes a liquid storage tank body, which serves as a storage chamber for storing liquid metal. The heat exchange pipe passes sequentially through the central axis of the heat storage tank body and the storage chamber. Inside the heat storage tank body, outside the heat exchange pipe, are sequentially arranged a vacuum layer one, a heat storage layer, an electric heating layer, a high-temperature insulation layer, and a vacuum layer two. The vacuum layer one is connected to the storage chamber through an air extraction hole. A piston for squeezing the liquid metal is provided inside the storage chamber.

[0008] Preferably, a heat-insulating end cap is provided between the bottom of the heat storage layer, the electric heating layer, the high-temperature heat insulation layer, the first vacuum layer, the second vacuum layer and the end cap of the heat storage tank.

[0009] Preferably, the material filling the heat storage layer is an aluminum-silicon alloy metal phase change material.

[0010] Preferably, the outer surface of the electric heating layer is made of stainless steel, and the inner surface is made of heating resistance wire.

[0011] Preferably, the high-temperature insulation layer and the insulation end cap are made of stainless steel, and their inner and outer layers have corrosion-resistant coatings and heat-insulating coatings.

[0012] Preferably, the contact surface between the heat exchange tube and the first vacuum layer, the inner wall of the first vacuum layer, the contact surface between the heat insulation end cap and the first vacuum layer, the inner wall of the storage chamber, and the contact surface between the piston and the storage chamber are all coated with a graphite-based corrosion-resistant coating.

[0013] Preferably, the liquid metal material in the storage chamber is a gallium-based alloy.

[0014] Preferably, a temperature sensor is installed inside the heat storage tank at the position in contact with the metal phase change material to measure the temperature of the metal phase change material.

[0015] (III) Beneficial Effects

[0016] This invention provides a compact automotive thermal storage device with controllable heat transfer across temperature zones. It features the following:

[0017] Beneficial effects:

[0018] 1. This compact automotive thermal energy storage device with cross-temperature zone controllable heat transfer utilizes a metal phase change material as the thermal energy storage medium. During charging, it converts electrical energy into heat energy and stores it. During heat release, the heat release power is adjusted by controlling the height of the liquid metal filling the vacuum layer. This prevents the coolant from boiling, allowing it to directly enter the device for high-power heat extraction. Furthermore, it allows for timely increases in the heat exchange area to maintain the device's heat release power when the stored heat decreases. This solves the problem of high-power coupling between high-temperature thermal energy storage devices and low-temperature heat-using equipment, while also enabling flexible output of heat release power. Attached Figure Description

[0019] Figure 1 This is an external isometric view of the present invention;

[0020] Figure 2 This is a half-section isometric view of the present invention;

[0021] Figure 3 This is the working state of the liquid metal power regulation in the vacuum layer of the present invention. Figure 1 ;

[0022] Figure 4 This is the working state of the liquid metal power regulation in the vacuum layer of the present invention. Figure 2 .

[0023] In the diagram: 1. Heat storage tank, 2. Heat exchange tube, 3. Heat storage layer, 4. Electric heating layer, 5. High temperature insulation layer, 6. Vacuum layer one, 7. Insulated end cap, 8. Heat storage tank end cap, 9. Liquid storage tank, 10. Storage chamber, 11. Piston, 12. Air extraction port, 13. Vacuum layer two. Detailed Implementation

[0024] This invention provides a compact automotive thermal storage device with controllable heat transfer across temperature zones, such as... Figure 1-4 As shown, it consists of three parts: a heat storage tank, a liquid storage tank, and a heat exchange tube 2.

[0025] The heat storage tank includes a heat storage tank body 1 and a heat storage tank end cap 8. The liquid storage tank includes a liquid storage tank body 9. The liquid storage tank body 9 is a storage chamber 10 for storing liquid metal. The heat exchange pipe 2 passes through the central axis of the heat storage tank body 1 and the storage chamber 10 in sequence. Inside the heat storage tank body 1, outside the heat exchange pipe 2, there are vacuum layer 6, heat storage layer 3, electric heating layer 4, high temperature insulation layer 5, and vacuum layer 13 for heat preservation in sequence. Vacuum layer 6 is connected to the storage chamber 10 through a vent hole 12. A piston 11 for squeezing liquid metal is provided inside the storage chamber 10. The piston 11 is controlled by a driver, which can be an electric push rod, a cylinder, or other power components.

[0026] A heat-insulating end cap 7 is provided between the bottom of the heat storage layer 3, the electric heating layer 4, the high-temperature insulation layer 5, the first vacuum layer 6, and the second vacuum layer 13 and the end cap 8 of the heat storage tank. It is used to isolate the phase change material and the liquid storage tank 9.

[0027] The material filling the heat storage layer 3 is an aluminum-silicon alloy (silicon content 12.6%) metallic phase change material with a phase change temperature of approximately 578℃, a latent heat of phase change of 515 kJ / kg, a specific heat capacity of 1.74 kJ / (kg·K) in the solid state, and 1.04 kJ / (kg·K) in the liquid state. The thermal conductivity is 180 W / mK in the solid state and 70 W / mK in the liquid state.

[0028] The outer surface of the electric heating layer 4 is made of corrosion-resistant and high-temperature resistant stainless steel, while the inner surface is made of heating resistance wire.

[0029] The high-temperature insulation layer 5 and the insulation end cap 7 are made of corrosion-resistant and high-temperature resistant stainless steel. Their inner and outer layers have corrosion-resistant coatings and insulation coatings, and the middle layer is a high-temperature resistant insulation material or a vacuum structure insulation material with a thermal conductivity of less than 0.05W / mK.

[0030] The contact surfaces of heat exchange tube 2 and vacuum layer 6, the inner wall of vacuum layer 6, the contact surfaces of heat insulation end cap 7 and vacuum layer 6, the inner wall of storage chamber 10, and the contact surfaces of piston 11 and storage chamber 10 are all coated with a graphite-based corrosion-resistant coating.

[0031] The liquid metal material in storage chamber 10 is a gallium-based alloy. Since gallium-based alloys are corrosive to ordinary metals, a graphite-based corrosion-resistant coating is required on the surfaces of vacuum layer 6, storage chamber 10, and piston 11 that come into contact with the liquid metal to prevent corrosion and extend the service life of the device.

[0032] A temperature sensor is installed inside the heat storage tank 1 at the location in contact with the metal phase change material to measure the temperature of the metal phase change material. The temperature sensor is connected to the terminal control system to calculate the real-time heat storage capacity. Based on the heating demand and the temperature of the metal phase change material, the bottom piston 11 is controlled to push the liquid metal into or out of the vacuum layer 6, changing the heat exchange area of ​​the device to adjust the heat release power and enable the device to operate in optimal condition.

[0033] Working principle:

[0034] When the device is in the off state, such as Figure 3 As shown, the liquid metal in storage chamber 10 is not pushed into vacuum layer 6 by piston 11. At this time, due to the heat insulation effect of vacuum layer 6, the contact area between heat storage layer 3 and heat exchange tube 2 is 0, and heat cannot be conducted to the coolant in heat exchange tube 2. Therefore, no heat exchange occurs in the device, and it is in a closed state. At the same time, due to the heat insulation effect of high-temperature insulation layer 5 and heat insulation end cap 7, the heat in heat storage layer 3 can be stored in the device for a long time without dissipating to the outside.

[0035] In power regulation mode, such as Figure 4 As shown, the liquid metal in storage chamber 10 is pushed into vacuum layer 6 by piston 11, creating a certain contact area between heat exchange tube 2 and heat storage layer 3. As the arrows in the figure represent the heat conduction process, heat storage layer 3 can conduct heat to the coolant through this contact area. Theoretically, since the height of the liquid metal pushed into vacuum layer 6 can be adjusted by piston 11, the heat exchange area between heat storage layer 3 and coolant can be adjusted from 0 to full area, and therefore the heat exchange power can also be adjusted from 0 to full power. In the initial stage of device operation, due to the extremely high temperature of heat storage layer 3, the heat exchange power is too high. To prevent the coolant from boiling, the heat exchange area of ​​the device can be adjusted to a smaller state by piston 11 to reduce the heat exchange power. After the device has been operating for a period of time, the temperature of heat storage layer 3 decreases, and the heat exchange power of the device decreases accordingly. The heat exchange area of ​​the device can be increased by piston 11 to compensate for the decreased heat power, thus achieving power regulation.

[0036] The best-practice application of this device is to provide winter heating for electric vehicles and to keep the batteries warm.

[0037] In cold winters, the driving range of electric vehicles decreases significantly, partly due to the reduced battery capacity at low temperatures and partly due to the high energy consumption of cabin heating. Connecting the heat exchange pipeline of this heat storage device to the electric vehicle's thermal management system allows for the distribution of cooling water to provide the necessary heat for cabin heating while simultaneously providing insulation for the battery. Using aluminum-silicon alloy as the metal phase change material, the material-level mass energy density can reach up to 280Wh / kg, and the volumetric energy density up to 700Wh / L, within an operating temperature range of 500℃. At the device level, the mass energy density can reach up to 200Wh / kg, and the volumetric energy density up to 400Wh / L, significantly exceeding the energy density of existing lithium batteries. The cost per unit energy storage capacity of this device is also lower than that of existing lithium batteries, and the materials used are primarily recyclable conventional metals, offering environmental benefits.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A compact automotive thermal storage device with controllable heat transfer across temperature zones, characterized in that: It includes a heat storage tank, a liquid storage tank and a heat exchange pipe (2). The heat storage tank includes a heat storage tank body (1) and a heat storage tank end cap (8). The liquid storage tank includes a liquid storage tank body (9). The liquid storage tank body (9) is a storage chamber (10) for storing liquid metal. The heat exchange pipe (2) passes through the central axis of the heat storage tank body (1) and the storage chamber (10) in sequence. Inside the heat storage tank body (1) outside the heat exchange pipe (2), there are vacuum layer one (6), heat storage layer (3), electric heating layer (4), high temperature insulation layer (5) and vacuum layer two (13) in sequence. Vacuum layer one (6) is connected to the storage chamber (10) through a vent hole (12). The storage chamber (10) is equipped with a piston (11) for squeezing liquid metal.

2. The compact automotive thermal storage device with cross-temperature zone controllable heat transfer according to claim 1, characterized in that: A heat-insulating end cap (7) is provided between the bottom of the heat storage layer (3), the electric heating layer (4), the high-temperature heat insulation layer (5), the first vacuum layer (6), the second vacuum layer (13) and the end cap (8) of the heat storage tank.

3. The compact automotive thermal storage device with cross-temperature zone controllable heat transfer according to claim 1, characterized in that: The material filled in the heat storage layer (3) is an aluminum-silicon alloy metal phase change material.

4. The compact automotive thermal storage device with cross-temperature zone controllable heat transfer according to claim 1, characterized in that: The outer surface of the electric heating layer (4) is stainless steel, and the inner surface is a heating resistance wire.

5. A compact automotive thermal storage device with controllable heat transfer across temperature zones according to claim 1, characterized in that: The high-temperature insulation layer (5) and the insulation end cap (7) are made of stainless steel, and their inner and outer layers have corrosion-resistant coatings and heat-insulating coatings.

6. A compact automotive thermal storage device with controllable heat transfer across temperature zones according to claim 2, characterized in that: The contact surfaces of the heat exchange tube (2) and the first vacuum layer (6), the inner wall of the first vacuum layer (6), the contact surfaces of the heat insulation end cap (7) and the first vacuum layer (6), the inner wall of the storage chamber (10), and the contact surfaces of the piston (11) and the storage chamber (10) are all coated with graphite-based corrosion-resistant coatings.

7. A compact automotive thermal storage device with controllable heat transfer across temperature zones according to claim 1, characterized in that: The liquid metal material in the storage chamber (10) is a gallium-based alloy.

8. A compact automotive thermal storage device with controllable heat transfer across temperature zones according to claim 3, characterized in that: A temperature sensor is installed inside the heat storage tank (1) at the position in contact with the metal phase change material to measure the temperature of the metal phase change material.

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