A cold region electric bus fast charging waste heat storage and release heating system and a heating method thereof

Abstract

The application discloses a kind of severe cold area electric bus fast charging waste heat storage and release heating system and its heating method, belong to energy-saving heating technical field, the system includes power battery pack, battery heat extraction module, phase change heat storage module, end heat pipe heat supplement module, vehicle cabin air duct, air outlet, vehicle bottom support and summer bypass heat exhaust channel.Bus service fast charging, heat extraction module recovers power battery waste heat and is transported to phase change heat storage module, relies on composite high thermal conductivity phase change material to store heat in sensible heat, latent heat mode, completes heat peak shaving and cross-period storage.In winter vehicle operation heating, heat storage module heats air duct by heat pipe module, air supply from air outlet to passenger leg area, auxiliary heating is assisted;After heat release of heat storage material is finished, original vehicle heating system independently heats.Summer cuts off heat supplement circuit, battery waste heat is directly discharged through bypass channel, and air duct receives original vehicle refrigeration cooling.The application realizes cross-stage storage of battery fast charging waste heat and vehicle cabin auxiliary heating.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving heating technology, specifically relating to a fast-charging waste heat storage and release heating system for electric buses in frigid regions and its heating method. Background Technology

[0002] With the increasing electrification of urban public transportation, electric buses have become an important component of urban public transportation in frigid regions. During winter operation, the usable capacity of the power battery decreases in low-temperature environments, and the passenger compartment experiences continuous heat loss due to heat dissipation from the enclosure structure, ventilation, and frequent door openings. The energy consumption for heating the passenger compartment directly consumes the power battery's charge, resulting in a decrease in driving range and operational stability.

[0003] Electric buses in frigid regions typically feature fixed routes, high-frequency departures, fast charging between trips, and continuous operation. When vehicles undergo high-rate fast charging at the terminal station or within the operating interval, the ohmic heat, polarization heat, and electrochemical reaction heat of the power battery are released in a concentrated manner within a short period of time; after the vehicle completes fast charging and enters the next trip, the passenger compartment requires continuous heating. Therefore, there is a significant temporal and spatial mismatch in the operation of electric buses in winter: temporally, battery waste heat is concentrated during the fast charging phase, while the demand for passenger compartment heating mainly occurs in the subsequent operation phase; spatially, the heat source is located in the power battery area under the vehicle, while the heat demand is located inside the passenger compartment, especially near the passengers' legs.

[0004] Existing power battery thermal management systems typically aim to reduce the battery's maximum temperature and improve temperature uniformity. They often employ liquid cooling plates, coolant circulation pipes, water pumps, reversing valves, radiators, or heat pump air conditioning modules to dissipate battery heat into the environment. While these solutions can meet battery heat dissipation requirements, the heat that must be dissipated during fast charging is usually not stored, and a stable heat release path for subsequent vehicle cabin heating is not established.

[0005] Existing technologies mainly include electric bus phase change energy storage heating technology and power battery waste heat composite thermal management technology.

[0006] Existing technology discloses a fast-charging latent heat storage heating system for all-electric city buses. This system uses a phase change energy storage unit as the heat source for heating the passenger compartment. When the vehicle stops at a charging station, the station infrastructure rapidly heats the energy storage unit. During vehicle operation, the phase change material releases heat for passenger compartment heating. This approach reduces the direct heating load on the onboard power battery, achieving some energy savings. However, the stored heat primarily originates from external heating equipment at the station, rather than the waste heat generated during the fast charging process of the power battery. It does not directly couple the battery fast-charging heat dissipation process, the phase change material heat storage process, and the passenger compartment ventilation duct heating process, thus failing to address the issue of unutilized battery waste heat during fast charging.

[0007] Existing technologies also disclose a composite thermal management system for power batteries. This system includes a water tank, a circulating pump, circulating fluid, a battery array, a heat spreader, and heat pipes. The cooling section of the heat pipes extends into the circulating fluid within the water tank, achieving heat dissipation, temperature difference control, preheating, and heat recycling of the power battery through the flow of the circulating fluid. Although this type of solution involves the recovery and utilization of power battery heat and can use some of the heat for vehicle cabin heating via a gas-liquid heat exchanger, its structure still revolves around an active liquid loop consisting of a water tank, circulating pump, circulating fluid, and gas-liquid heat exchanger. The heating process mainly relies on real-time heat transfer during operation, lacking a phase change material heat storage chamber for cross-stage heat storage, and failing to establish a passive structural connection path of "battery heat extraction—PCM heat storage—original vehicle sidewall lower edge air duct heat replenishment."

[0008] Therefore, although existing technologies involve phase change energy storage heating for electric buses and waste heat utilization from power batteries, they still have the following shortcomings. First, phase change heating solutions for electric buses mostly rely on station-end heat sources and do not directly recover waste heat from fast charging of power batteries. Second, waste heat utilization solutions for power batteries mostly rely on active loops such as circulating pumps, circulating liquids, and gas-liquid heat exchangers, which are relatively complex in structure and control. Third, existing solutions do not address the time-domain mismatch problem of "centralized heat generation during fast charging between trips and continuous heating during the transition period" for electric buses in severely cold regions, and do not propose a passive heat storage and release heating system composed of a battery heat extraction module, a phase change material heat storage module, and a heat replenishment module for the lower edge of the original vehicle side wall air duct. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a fast-charging waste heat storage and release heating system and its heating method for electric buses in extremely cold regions. This system connects battery heat extraction, phase change heat storage, and duct supplementary heat transfer into a continuous heat transfer path. This allows the waste heat from the power battery that needs to be discharged during the fast-charging phase to be first extracted and stored in the phase change heat storage structure under the vehicle. Then, during the vehicle's continuous operation phase, it is released to the lower edge of the side wall duct of the passenger compartment, where it is carried by the existing airflow from the original vehicle heating system to the passenger leg area. This achieves cross-stage storage and auxiliary heating of the fast-charging waste heat.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A fast-charging waste heat storage and release heating system for electric buses in frigid regions includes a power battery pack, a battery heat extraction module, a phase change material heat storage module, a terminal heat pipe array heat replenishment module, an air duct along the lower edge of the side wall of the passenger compartment, an air outlet, a passenger compartment floor, a mounting bracket under the vehicle, and a bypass heat exhaust channel in summer. The battery heating module is installed between the power battery pack and the phase change material heat storage module. The battery heating module is thermally connected to the power battery pack, and the phase change material heat storage module is thermally connected to the battery heating module. One end of the terminal heat pipe array heat replenishment module is thermally connected to the phase change material heat storage module, and the other end extends into the air duct along the lower edge of the side wall of the vehicle compartment. The air duct along the lower edge of the side wall of the vehicle compartment is connected to the air outlet. Excess heat generated by the fast charging of the power battery pack is directly dissipated to the outside environment through the summer bypass heat dissipation channel. The power battery pack is arranged in the under-car battery installation area below the vehicle floor, and the phase change material thermal storage module is fixedly installed in the unused interlayer space between the power battery pack and the vehicle floor through the under-car mounting bracket.

[0011] A further improvement of the present invention is that the power battery pack includes several blade batteries, which are divided into four groups of independent auxiliary heating units with completely identical structures and parameters. The four groups of auxiliary heating units work together to complete the storage of waste heat from fast charging and the auxiliary heating of the vehicle compartment during vehicle operation.

[0012] A further improvement of the present invention is that the battery heating module includes multiple flat heating pipes. The evaporation section of the flat heating pipes is attached to and clamped in the narrow slit on the side of the blade battery and the main heat generation area of ​​the battery. The contact surface between the evaporation section and the blade battery is filled with thermally conductive silicone grease to reduce the interfacial contact thermal resistance. The condensation section of the flat heating pipes is embedded in the internal cavity of the phase change material heat storage module.

[0013] A further improvement of the present invention is that the phase change material thermal storage module includes a thermal storage cavity, a composite high thermal conductivity phase change material, an outer sealing structure, and a thermal insulation layer. The heat storage cavity is closely fitted to the condensation section of the battery heat extraction module on the side closest to the power battery pack for heat conduction. The heat storage cavity is connected to the evaporation section of the terminal heat pipe array heat replenishment module on the side closest to the side wall of the vehicle compartment along the air duct. Composite high thermal conductivity phase change material is filled inside the heat storage cavity to absorb and temporarily store the waste heat transported by the battery heat extraction module during the fast charging stage. The outer sealing structure prevents the phase change material from leaking out, and the outer side is covered with a heat insulation layer to reduce non-target heat loss during the heat storage process.

[0014] A further improvement of the present invention is that the heat storage cavity in the phase change material heat storage module is a flat metal cavity.

[0015] A further improvement of the present invention is that the composite high thermal conductivity phase change material is a paraffin-expanded graphite-based shaped composite phase change material, in which expanded graphite forms a thermally conductive skeleton inside the phase change material and restricts the flow of liquid paraffin.

[0016] A further improvement of this invention is that carbon nanotubes and graphene are also added to the paraffin-expanded graphite-based shaped composite phase change material.

[0017] A further improvement of the present invention is that the terminal heat pipe array heat replenishment module includes multiple heat replenishment heat pipes and air-side heat exchange fins; the evaporation section of the heat replenishment heat pipe is inserted into the heat storage cavity of the phase change material heat storage module and fully contacts the composite high thermal conductivity phase change material for heat exchange; the insulation section of the heat replenishment heat pipe is bent 90° in the vertical direction and extends upward through the pre-reserved assembly gap between the vehicle bottom and the side wall of the vehicle compartment; the condensation section of the heat replenishment heat pipe extends into the interior of the air duct along the lower edge of the side wall of the vehicle compartment; and the heat exchange fins are fixed to the outer wall of the condensation section to increase the air convection heat exchange area of ​​the air duct.

[0018] A further improvement of the present invention is that the air duct along the lower edge of the side wall of the carriage is arranged in the lower part of the side wall of the carriage and in the leg area below the passenger seat. The air inlet end of the air duct along the lower edge of the side wall of the carriage is connected to the original vehicle heating air supply pipeline, and the air outlet end is connected to the air outlet.

[0019] A heating method for a fast-charging waste heat storage and release heating system for electric buses in frigid regions includes: S1: After the vehicle enters the fast charging mode between shifts, the waste heat generated by the power battery pack is absorbed by the battery heat collection module. S2: The battery heat extraction module transfers the heat generated by the power battery pack to the phase change material heat storage module. S3: The composite high thermal conductivity phase change material in the phase change material thermal storage module absorbs the waste heat of fast charging through sensible heat and latent heat of phase change, realizing heat input buffering, peak shaving and cross-stage storage; S4: After the vehicle departs and enters the winter operation phase, the original vehicle heating system is turned on, and airflow is formed in the air duct along the lower edge of the side wall of the passenger compartment. S5: The heat in the phase change material thermal storage module is transferred to the air duct along the lower edge of the side wall of the carriage through the terminal heat pipe array heat replenishment module; S6: Airflow through the duct passes through the terminal heat pipe array heating module and is heated, and then sent to the passenger leg area through the air outlet to form auxiliary heating; S7: When the temperature of the phase change material heat storage module drops to a level that cannot meet the heat replenishment requirements, the system will naturally stop releasing heat, and the original vehicle heating system will continue to bear the heating load of the vehicle compartment. S8: During summer operation, the supplementary heating circuit is closed or isolated, and the heat from the battery side is discharged outside the vehicle through the summer bypass heat dissipation channel. The air duct along the lower edge of the side wall of the vehicle is still cooled by the original vehicle cooling system.

[0020] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The present invention forms a continuous heat transfer path of “battery heat extraction - PCM heat storage - air duct side array heat replenishment”, which transforms the battery waste heat that originally needed to be dissipated during the fast charging stage into an auxiliary heating heat source that can be used during the vehicle’s continuous operation.

[0021] (2) The present invention uses heat pipes for heat extraction on the battery side and heat transfer from the heat storage end to the air duct end, without adding an independent liquid circulation pump; the air side heat exchange utilizes the existing airflow of the original vehicle heating system, without adding a dedicated supplementary heating fan, resulting in a compact structure, low additional energy consumption, and high reliability.

[0022] (3) In view of the characteristics of blade battery with long size, narrow gap and uneven heat generation during fast charging, the present invention sets up a heat pipe gradient arrangement of high heat zone, transition zone and peripheral zone, so that the number of heat collection components matches the local heat load, which helps to alleviate heat accumulation during fast charging.

[0023] (4) The present invention arranges the heat storage cavity in the available space between the battery area under the vehicle and the floor of the vehicle, and the end heat supplementation heat pipe is connected to the air duct along the lower edge of the side wall of the vehicle at a short distance, which does not occupy the passenger space and can send auxiliary warm air to the passenger's leg area.

[0024] (5) The present invention adopts a modular auxiliary heating unit, which can be adapted to the battery pack size and vehicle air duct layout in a modular way, which facilitates vehicle integration and subsequent promotion.

[0025] (6) The present invention is designed with a bypass heat dissipation method in summer. In summer, only the heat from the battery side is discharged outside the vehicle through the bypass heat dissipation channel, while the original air ducts inside the vehicle are still cooled by the original vehicle cooling system, thus avoiding the waste heat from fast charging from entering the vehicle compartment.

[0026] (7) Through theoretical calculation, simulation and scaled-down experiments, the waste heat utilization rate of the system can reach 70.7%; in the embodiment where the stable heating load of the whole vehicle is 20kW and the design supplementary heating power of the four auxiliary heating units is about 1.72kW, the theoretical heating load compensation ratio is about 8.6%.

[0027] In summary, this invention uses heat pipes to introduce waste heat from the power battery into a phase change material heat storage cavity during the fast charging phase, and releases heat to the lower part of the vehicle compartment through the terminal heat pipe array and the air duct along the lower side wall of the original vehicle during the vehicle operation phase, thereby realizing cross-stage storage of waste heat from battery fast charging and auxiliary heating of the vehicle compartment. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a system workflow diagram of the present invention, used to illustrate the heat transfer path in the fast charging and thermal storage stage and the operation and reheating stage.

[0030] Figure 2This is a schematic diagram and physical model of the system structure of the present invention, used to illustrate the relative positions between the power battery pack, the battery heat extraction module, the PCM heat storage module, the terminal heat pipe array heat replenishment module, the air duct along the lower edge of the side wall of the carriage, and the air supply area for the passenger's legs.

[0031] Figure 3 This is a flowchart for the feasibility verification of the system of the present invention, used to illustrate the verification logic of theoretical calculation, PCM capacity estimation, expected heating effect, fast charging thermal storage simulation and operation heat replenishment simulation.

[0032] Figure 4 The diagram shows the simulation results of the system of this invention, used to illustrate the simulation results of the two stages: fast charging thermal storage and operation reheating.

[0033] Figure 5 This is a scaled-down experimental temperature curve of the present invention, used to illustrate the test results of the battery simulation block, PCM, heat pipe end, and air duct temperature.

[0034] Explanation of reference numerals in the attached figures: 1. Power battery pack; 2. Battery heat extraction module; 3. Phase change material heat storage module; 4. Terminal heat pipe array heat replenishment module; 5. Air duct along the lower edge of the side wall of the vehicle compartment; 6. Air outlet; 7. Vehicle compartment floor; 8. Undercarriage mounting bracket; 9. Summer bypass heat exhaust channel. Detailed Implementation

[0035] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0042] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0043] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0044] Example 1 This invention provides a fast-charging waste heat storage and release heating system for electric buses in extremely cold regions, comprising a power battery pack 1, a battery heat extraction module 2, a phase change material heat storage module 3, a terminal heat pipe array supplementary heat module 4, a lower edge air duct along the side wall of the passenger compartment 5, an air outlet 6, a passenger compartment floor 7, a mounting bracket under the vehicle 8, and a summer bypass heat exhaust channel 9. The battery heat extraction module 2 is thermally connected to the power battery pack 1, the phase change material heat storage module 3 is thermally connected to the battery heat extraction module 2, one end of the terminal heat pipe array supplementary heat module 4 is thermally connected to the phase change material heat storage module 3, and the other end extends into the lower edge air duct along the side wall of the passenger compartment 5, which is connected to the air outlet 6. Thus, the power battery pack 1, battery heat extraction module 2, phase change material heat storage module 3, terminal heat pipe array supplementary heat module 4, lower edge air duct along the side wall of the passenger compartment 5, and air outlet 6 sequentially form a heat transfer path of "battery heat extraction—phase change material heat storage—air duct supplementary heat."

[0045] System composition and connection relationship The power battery pack 1 is located in the under-vehicle battery installation area below the vehicle floor 7. In one embodiment, the power battery pack 1 contains 400 blade batteries, which are divided into four independent auxiliary heating units with identical structures and parameters. Each auxiliary heating unit is equipped with 100 blade batteries. The four auxiliary heating units work together to complete the storage of waste heat from fast charging and the auxiliary heating of the vehicle compartment during vehicle operation.

[0046] The battery heat extraction module 2 is assembled between the power battery pack 1 and the phase change material heat storage module 3, achieving tight thermal coupling between the two. The battery heat extraction module 2 includes multiple flat heat extraction pipes. The evaporation section of the flat heat extraction pipes is attached to and clamped in the narrow slit on the side of the blade battery and the main heat-generating area of ​​the battery. The contact surface between the evaporation section and the blade battery is filled with thermally conductive silicone grease to reduce the interfacial contact thermal resistance. The condensation section of the flat heat extraction pipes is embedded in the internal cavity of the phase change material heat storage module 3. Under fast charging conditions, the Joule heat and polarization heat generated by the power battery pack 1 can be quickly conducted to the phase change material heat storage module 3 through the flat heat extraction pipes to complete the heat transfer.

[0047] The phase change material (PCM) thermal storage module 3 is fixedly installed in the unused interlayer space between the power battery pack 1 and the vehicle floor 7 via a vehicle undermount bracket 8. It is bidirectionally connected to the battery heat extraction module 2 and the terminal heat pipe array heat replenishment module 4. The PCM thermal storage module 3 consists of a flat sealed thermal storage cavity, a composite high thermal conductivity PCM material, an outer sealing structure, and a thermal insulation layer. The side of the thermal storage cavity closest to the power battery pack 1 is in close contact with the condensation section of the battery heat extraction module 2 for thermal conduction. The side of the thermal storage cavity closest to the lower edge of the side wall of the vehicle compartment is used for insertion and connection of the evaporation section of the terminal heat pipe array heat replenishment module 4. The composite high thermal conductivity PCM material is filled inside the thermal storage cavity to absorb and temporarily store the waste heat transported by the battery heat extraction module 2 during the fast charging stage. The outer sealing structure prevents leakage of the PCM material, and the outer thermal insulation layer reduces non-target heat loss during the thermal storage process.

[0048] The terminal heat pipe array heat replenishment module 4 is installed between the phase change material heat storage module 3 and the lower edge air duct 5 of the side wall of the vehicle, realizing the heat transfer from the heat storage unit to the air duct of the vehicle. The terminal heat pipe array heat replenishment module 4 consists of multiple heat replenishment heat pipes and air-side heat exchange fins. The evaporation section of the heat replenishment heat pipe is inserted into the heat storage cavity of the phase change material heat storage module 3 and makes full contact with the composite high thermal conductivity phase change material for heat exchange. The insulation section of the heat replenishment heat pipe is bent 90° vertically and extends upward through the pre-reserved assembly gap between the vehicle bottom and the side wall of the vehicle. The condensation section of the heat replenishment heat pipe extends into the lower edge air duct 5 of the side wall of the vehicle. The outer wall of the condensation section is fixed with heat exchange fins to increase the air convection heat exchange area of ​​the air duct.

[0049] The lower side wall air duct 5 is an inherent structure of the original electric bus's heating air duct, located in the lower part of the side wall of the passenger compartment, under the leg area of ​​the passenger seats. The air inlet of the lower side wall air duct 5 is connected to the original vehicle's heating air supply pipeline, and the air outlet is connected to the air outlet 6. Under winter vehicle operating conditions, the original vehicle heating system drives the airflow to continuously flow through the condensation section of the terminal heat pipe array supplementary heating module 4. After absorbing the stored heat released by the heat pipes, the airflow is blown towards the passenger leg area through the air outlet 6, completing the auxiliary heating of the passenger compartment.

[0050] In the implementation of the summer bypass heat dissipation channel 9, the heat conduction path between the phase change material heat storage module 3 and the lower edge air duct 5 of the side wall of the vehicle is physically isolated and cut off during summer operation. The excess heat generated by the fast charging of the power battery pack 1 is directly dissipated to the outside environment through the summer bypass heat dissipation channel 9. The lower edge air duct 5 of the side wall of the vehicle is only connected to the original vehicle cooling system and does not participate in the heat storage and heat release cycle, so as to avoid the input of fast charging waste heat into the vehicle and increase the temperature inside the vehicle, while not changing the original vehicle summer cooling air supply logic.

[0051] Gradient arrangement of battery heat collection modules Considering the uneven heat distribution within the power battery pack 1, the batteries in each auxiliary heating unit can be divided into a high-heat zone, a transition zone, and an outer zone based on the temperature field distribution. The high-heat zone accounts for approximately 30% of the cell area, the transition zone accounts for approximately 40%, and the outer zone accounts for approximately 30%.

[0052] In one embodiment, each battery cell in the high-heat zone is equipped with three flat heat pipes, each battery cell in the transition zone is equipped with two flat heat pipes, and each battery cell in the outer zone is equipped with one flat heat pipe. This gradient arrangement matches the number of heat-collecting components with the local heating intensity, which can both enhance heat collection in the central high-heat zone and reduce redundant arrangement in the outer low-heat zone, thereby improving the efficiency of battery waste heat removal during fast charging and improving the temperature uniformity of the battery pack.

[0053] Implementation of Phase Change Material Thermal Storage Module The heat storage cavity in the phase change material heat storage module 3 is preferably a flat metal cavity. The thickness of the heat storage cavity is adapted to the limited installation space under the vehicle, while its length and width match the corresponding auxiliary heating unit. In one embodiment, the heat storage cavity can be divided into four groups, each corresponding to one of the four auxiliary heating units. Each heat storage cavity is externally equipped with a sealing structure and a thermal insulation layer to reduce non-target heat dissipation during the fast charging heat storage stage and before heat release during operation.

[0054] The composite high thermal conductivity phase change material is preferably a paraffin-expanded graphite-based shaped composite phase change material with a phase change temperature of approximately 35 °C. Expanded graphite forms a thermally conductive framework within the phase change material and restricts the flow of liquid paraffin. Depending on the thermal conductivity requirements, thermally enhanced components such as carbon nanotubes and graphene can be further added. During the fast charging phase, this material absorbs waste heat from the battery through sensible heat rise and latent heat of phase change, and during the operation phase, it releases heat to the end-of-line heat pipe array heating module 4.

[0055] The heating method of the present invention includes the following steps: S1: After the vehicle enters the fast charging mode between shifts, the waste heat generated by the power battery pack 1 is absorbed by the battery heat collection module 2.

[0056] S2: The battery heat extraction module 2 transfers the heat generated by the power battery pack 1 to the phase change material heat storage module 3.

[0057] S3: The composite high thermal conductivity phase change material in the phase change material thermal storage module 3 absorbs fast-charging waste heat through sensible heat and latent heat of phase change, realizing heat input buffering, peak shaving and cross-stage storage.

[0058] S4: After the vehicle departs and enters the winter operation phase, the original vehicle heating system is turned on, and airflow is formed in the air duct 5 along the lower edge of the side wall of the passenger compartment.

[0059] S5: The heat in the phase change material thermal storage module 3 is transferred to the air duct 5 along the lower edge of the side wall of the carriage through the terminal heat pipe array heat replenishment module 4.

[0060] S6: Airflow through the duct passes through the terminal heat pipe array supplementary heating module 4 and is heated, and then sent to the passenger leg area through the air outlet 6 to form auxiliary heating.

[0061] S7: When the temperature of the phase change material heat storage module 3 drops to a level that cannot meet the heat replenishment requirements, the system will naturally stop effectively releasing heat, and the original vehicle heating system will continue to bear the heating load of the vehicle compartment.

[0062] S8: During summer operation, the supplementary heating circuit is closed or isolated, and the heat from the battery side is discharged outside the vehicle through the summer bypass heat exhaust channel 9. The air duct 5 along the lower edge of the side wall of the vehicle is still cooled by the original vehicle cooling system.

[0063] Key technical parameters and calculation basis In one embodiment, the system uses 400 blade batteries as the calculation object of the power battery pack and divides them into four identical auxiliary heating units, each corresponding to 100 blade batteries. The capacity of a single blade battery is 135 Ah, the DC internal resistance is 0.5 mΩ, the fast charging rate is 2 C, and the fast charging time is 30 min. Using ohmic heat as the main heat source during the fast charging stage, the heat generation of a single blade battery during fast charging is estimated according to formula (1):

[0064] In the formula, The heat generated during fast charging of a single blade battery For fast charging current, The battery's DC internal resistance, This refers to the fast charging time. Based on the above parameters, the heat generated during fast charging of a single blade battery is approximately 65 kJ, and the total heat input of a single auxiliary heating unit during the fast charging phase is approximately 6.5 MJ.

[0065] To cover the heat input of a single fast charge and reserve a certain margin of heat storage capacity, the mass of phase change material required for a single auxiliary heating unit is estimated according to equation (2):

[0066] In the formula, m is the mass of phase change material required for a single auxiliary heating unit, Qu is the total heat input of a single auxiliary heating unit during the fast charging stage, δ is the heat storage capacity margin coefficient, L is the latent heat of phase change per unit mass of phase change material, cp is the specific heat capacity of phase change material, Tm is the phase change temperature, and T0 is the initial temperature.

[0067] In one embodiment, Qu = 6.5 MJ, δ = 0.082, L = 190 kJ / kg, cp = 2.3 kJ / (kg·K), Tm = 308.15 K, and T0 = 273.15 K are used. It is estimated that the PCM required for a single auxiliary heating unit is approximately 26 kg, corresponding to a theoretical heat storage capacity of approximately 7.03 MJ, which can cover a single fast-charging heat input of 6.5 MJ.

[0068] During the reheating phase, a single auxiliary heating unit primarily serves the air zone beneath the two rows of seats. This area has an effective volume of approximately 1.5 m³. 3 The effective air outlet area is taken as 0.03 m², and the volumetric flow rate is taken as 0.01 m³. 3 / s, corresponding to an average outlet air velocity of approximately 0.33 m / s, which can be controlled within the range of 0.3 to 0.4 m / s. The theoretical effective heating power on the air side is estimated according to formula (3):

[0069] In the formula, P is the theoretical effective heating power on the air side, ρ is the air density, ca is the specific heat capacity of air, qv is the air volumetric flow rate, and ΔT is the air temperature rise.

[0070] In one embodiment, ρ is taken as 1.29 kg / m 3 , ca = 1000 J / (kg·K), qv = 0.01 m 3 / s, ΔT = 30 K. It is estimated that the theoretical effective heating power of a single auxiliary heating unit on the air side is approximately 387 W, and the total effective heating power of the four auxiliary heating units is approximately 1.55 kW. Considering airflow heat dissipation, incomplete heat exchange via heat pipes, and structural design margins, the designed heat extraction power on the heat storage side of a single auxiliary heating unit is approximately 430 W, and the total designed heat extraction power of the four auxiliary heating units is approximately 1.72 kW.

[0071]

[0072] Example 2 like Figure 1 and Figure 2As shown, this embodiment provides a fast-charging waste heat storage and release heating system for electric buses in extremely cold regions. The power battery pack 1 is located below the vehicle floor 7. The battery heat extraction module 2 is located on the side of the power battery pack 1. The evaporation section of the flat heat extraction heat pipe in the battery heat extraction module 2 is in contact with the main heat-generating area of ​​the blade battery. The condensation section of the supplementary heat extraction module 4 is inserted into or embedded in the heat storage cavity of the phase change material heat storage module 3. The phase change material heat storage module 3 is fixed in the space between the battery area under the vehicle and the vehicle floor 7 by a vehicle under-mount bracket 8. The cavity of the heat storage module 3 is filled with a composite high thermal conductivity phase change material, and a sealing structure and insulation layer are provided on the outside of the heat storage cavity.

[0073] The terminal heat pipe array heat replenishment module 4 is located between the phase change material heat storage module 3 and the lower edge air duct 5 of the side wall of the passenger compartment. The evaporation section of the heat pipe in the heat replenishment module 4 is embedded in the heat storage cavity and contacts the composite high thermal conductivity phase change material; the insulation section of the heat replenishment heat pipe bends upward from the bottom of the vehicle and extends through a short installation gap between the bottom of the vehicle and the side wall of the passenger compartment to the lower edge air duct 5 of the side wall of the passenger compartment; the condensation section of the heat replenishment heat pipe extends into the lower edge air duct 5 of the side wall of the passenger compartment, and air-side heat exchange fins are fixed on the outer surface of the condensation section. The lower edge air duct 5 of the side wall of the passenger compartment is connected to the original vehicle heating system and delivers air to the passenger leg area through the air outlet 6.

[0074] In one embodiment, the terminal heat pipe array supplementary heating module 4 adopts a 3×8 array of supplementary heating heat pipes. The evaporation section of each supplementary heating heat pipe in the array is thermally connected to the heat storage cavity, and each condensation section is located in the air duct 5 along the lower side wall of the vehicle compartment. The air-side heat exchange fins are arranged along the airflow direction of the air duct, so that the air provided by the original vehicle heating system can flow through multiple heat pipe condensation sections in sequence and obtain supplementary heat.

[0075] like Figure 1 As shown, during the fast-charging heat storage stage, the vehicle is parked and undergoing fast charging. The heat generated by the power battery pack 1 is absorbed by the evaporation section of the flat heat pipe and transferred to the heat storage chamber by the condensation section. The composite high thermal conductivity phase change material heats up and undergoes a phase change within the heat storage chamber, completing the absorption, buffering, and storage of waste heat from fast charging. This stage mainly addresses the problem of heat accumulation during battery fast charging and provides a heat source for subsequent vehicle operation.

[0076] like Figure 2 As shown, during the reheating phase, after the vehicle departs, the original vehicle heating system is activated, creating airflow within the air duct 5 along the lower side wall of the passenger compartment. Heat from the heat storage chamber is transferred via the reheating heat pipe to the condenser section located within the air duct. The air is heated as it flows through the condenser section and the air-side heat exchange fins, and then delivered to the passenger leg area through the air outlet 6. This phase does not require an additional liquid circulation pump or dedicated reheating fan.

[0077] During summer operation, the system does not release fast-charging waste heat to the lower edge of the side wall of the vehicle compartment duct 5. Through structures such as thermal isolation, bypass valves or bypass ventilation ducts, the heat from the battery side is discharged outside the vehicle through the summer bypass heat dissipation channel 9; the lower edge of the side wall of the vehicle compartment duct 5 is still cooled by the original vehicle cooling system, thereby preventing the stored heat from entering the vehicle compartment.

[0078] like Figures 3 to 5 As shown, this embodiment verifies the system's feasibility through theoretical calculations, simulation analysis, and scaled-down experiments. In the fast-charging thermal storage simulation, the battery temperature drops from 60°C to 38°C, and the PCM temperature rises from 15°C to 40°C, with the system reaching thermal equilibrium in approximately 1000 seconds. The operational heat replenishment simulation uses an equivalent simplified heat pipe model to verify the air duct temperature rise trend; after 900 seconds, the average temperature of the air mass at the end rises by approximately 7°C. In the scaled-down experiment, a 120W heating process is used for 30 minutes to simulate the fast-charging heat generation process, followed by a 45-minute cooling process using a fan after heating to simulate the operational heat replenishment process. The results show that the battery simulation block temperature drops from 70°C to approximately 45°C, the heat pipe end temperature remains above 35°C, and the air temperature inside the air duct remains above 30°C.

[0079]

[0080] The inventive points protected by this invention are as follows: 1. An overall architecture for a fast-charging waste heat storage and release heating system for electric buses in frigid regions, which constructs an integrated passive heat pipe heat transfer path of "battery heat extraction - phase change heat storage - air duct array heat replenishment" to recover waste heat from fast-charging power batteries for auxiliary heating of the bus compartment across different time periods; 2. The blade battery gradient heat pipe heat extraction arrangement structure divides the battery into high heat zone, transition zone and peripheral zone according to the intensity of battery heating, and differentiates the number of flat heat extraction heat pipes to balance the battery temperature field and improve waste heat removal efficiency. 3. The undercarriage sandwich modular phase change thermal storage unit layout adopts paraffin-expanded graphite composite high thermal conductivity shaped phase change material, and is equipped with a sealed and heat-insulating cavity to achieve fast-charging heat peak shaving and cross-shift storage; 4. The bent-end heat pipe array air duct heat replenishment structure has a heat pipe insulation section bent at 90° and connected to the original vehicle side wall lower leg air duct. The condensation section integrates heat exchange fins, reuses the original vehicle warm air flow to achieve passive heating, and does not require an additional fan or liquid pump. 5. Dual-mode thermal circuit switching structure for winter and summer. In summer, a bypass heat exhaust channel is set up to isolate the heat storage module from the vehicle air duct. Waste heat from fast charging is directly discharged outside the vehicle without interfering with the original vehicle cooling system. 6. The modular design of four independent auxiliary heating units, each unit is matched with 100 blade batteries, which can be flexibly adapted and integrated according to the bus battery pack and air duct size; 7. Supporting a fast-charging waste heat storage and release heating method for electric buses in frigid regions, including the entire process control steps of fast-charging heat storage, winter heat release heating, and summer bypass heat exhaust; 8. A complete set of capacity and power calculation and matching methods based on battery ohmic heat, latent heat of phase change, and air heat exchange in the duct, to achieve quantitative design of PCM thermal storage quality and heating supplementary power.

[0081] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0082] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A fast-charging waste heat storage and release heating system for electric buses in frigid regions, characterized in that, It includes a power battery pack (1), a battery heat extraction module (2), a phase change material heat storage module (3), a terminal heat pipe array heat replenishment module (4), a side wall lower edge air duct (5), an air outlet (6), a car floor (7), a vehicle bottom mounting bracket (8), and a summer bypass heat exhaust channel (9). The battery heating module (2) is installed between the power battery pack (1) and the phase change material heat storage module (3). The battery heating module (2) is thermally connected to the power battery pack (1), and the phase change material heat storage module (3) is thermally connected to the battery heating module (2). One end of the end heat pipe array heat supplement module (4) is thermally connected to the phase change material heat storage module (3), and the other end extends into the lower edge air duct (5) of the side wall of the vehicle. The lower edge air duct (5) of the side wall of the vehicle is connected to the air outlet (6). The excess heat generated by the fast charging of the power battery pack (1) is directly dissipated to the outside environment through the summer bypass heat dissipation channel (9). The power battery pack (1) is arranged in the undercarriage battery installation area below the vehicle floor (7). The phase change material heat storage module (3) is fixedly installed in the idle interlayer space between the power battery pack (1) and the vehicle floor (7) by the undercarriage mounting bracket (8).

2. The fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 1, characterized in that, The power battery pack (1) contains several blade batteries, which are divided into four groups of independent auxiliary heating units with identical structures and parameters. The four auxiliary heating units work together to complete the storage of waste heat during fast charging and the auxiliary heating of the vehicle compartment during vehicle operation.

3. A fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 2, characterized in that, The battery heat extraction module (2) includes multiple flat heat extraction tubes. The evaporation section of the flat heat extraction tubes is attached to and clamped in the narrow slit on the side of the blade battery and the main heat generation area of ​​the battery. The contact surface between the evaporation section and the blade battery is filled with thermally conductive silicone grease to reduce the interfacial contact thermal resistance. The condensation section of the flat heat extraction tubes is embedded in the internal cavity of the phase change material heat storage module (3).

4. The fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 1, characterized in that, The phase change material thermal storage module (3) includes a thermal storage cavity, a composite high thermal conductivity phase change material, an outer sealing structure, and a thermal insulation layer; The heat storage cavity is closely fitted with the condensation section of the battery heat extraction module (2) on the side close to the power battery pack (1) for heat conduction. The heat storage cavity is close to the side of the lower edge of the air duct (5) of the side wall of the vehicle compartment for the evaporation section of the end heat pipe array heat supplement module (4) to be inserted and plugged in. The composite high thermal conductivity phase change material is filled inside the heat storage cavity to absorb and temporarily store the waste heat transported by the battery heat extraction module (2) during the fast charging stage. The outer sealing structure prevents the phase change material from leaking. The outer side is covered with a heat insulation layer to reduce non-target heat dissipation loss during the heat storage process.

5. A fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 4, characterized in that, The heat storage cavity in the phase change material heat storage module (3) is a flat metal cavity.

6. A fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 4, characterized in that, The composite high thermal conductivity phase change material is a paraffin-expanded graphite-based shaped composite phase change material. The expanded graphite forms a thermally conductive skeleton inside the phase change material and restricts the flow of liquid paraffin.

7. A fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 6, characterized in that, The paraffin-expanded graphite-based shaped composite phase change material also contains carbon nanotubes and graphene.

8. A fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 1, characterized in that, The terminal heat pipe array heat replenishment module (4) includes multiple heat replenishment heat pipes and air-side heat exchange fins; the heat replenishment heat pipe evaporation section is inserted into the heat storage cavity of the phase change material heat storage module (3) and fully contacts the composite high thermal conductivity phase change material for heat exchange; the heat replenishment heat pipe insulation section is bent 90° in the vertical direction and extends upward through the pre-reserved assembly gap between the bottom of the vehicle and the side wall of the car body; the heat replenishment heat pipe condensation section extends into the interior of the air duct (5) under the side wall of the car body; the outer wall of the condensation section is fixed with heat exchange fins to increase the air convection heat exchange area of ​​the air duct.

9. A fast-charging waste heat storage and release heating system for electric buses in frigid regions according to claim 1, characterized in that, The lower edge air duct (5) of the side wall of the carriage is located in the lower part of the side wall of the carriage and in the leg area under the passenger seat. The air inlet of the lower edge air duct (5) of the side wall of the carriage is connected to the original vehicle heating air supply pipeline, and the air outlet is connected to the air outlet (6).

10. A heating method for a fast-charging waste heat storage and release heating system for electric buses in frigid regions, as described in any one of claims 1 to 9, characterized in that... include: S1: After the vehicle enters the inter-shift fast charging mode, the waste heat generated by the power battery pack (1) is absorbed by the battery heat collection module (2); S2: The battery heat extraction module (2) transfers the heat generated by the power battery pack (1) to the phase change material heat storage module (3). S3: The composite high thermal conductivity phase change material in the phase change material thermal storage module (3) absorbs the waste heat of fast charging through sensible heat and latent heat of phase change, realizing heat input buffering, peak shaving and cross-stage storage; S4: After the vehicle departs and enters the winter operation phase, the original vehicle heating system is turned on, and airflow is formed in the air duct (5) along the lower edge of the side wall of the carriage. S5: The heat in the phase change material heat storage module (3) is transferred to the air duct (5) along the lower edge of the side wall of the carriage through the terminal heat pipe array heat replenishment module (4); S6: The air in the duct flows through the end heat pipe array supplementary heating module (4) and is heated, and then sent into the passenger leg area through the air outlet (6) to form auxiliary heating; S7: When the temperature of the phase change material heat storage module (3) drops to the point where it cannot meet the heat replenishment requirements, the system will naturally stop releasing heat, and the original vehicle owner heating system will continue to bear the heating load of the vehicle compartment. S8: During summer operation, the supplementary heating circuit is closed or isolated, and the heat on the battery side is discharged outside the vehicle through the summer bypass heat exhaust channel (9). The air duct (5) along the lower edge of the side wall of the vehicle is still cooled by the original vehicle cooling system.

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