An integrated design method for power system cooling unit considering phase change heat storage

Abstract

The present invention relates to an integrated design method for a power system cooling unit taking into account phase change heat storage, comprising: S1, establishing a phase change material candidate information library; S2, selecting one of the phase change heat storage materials from the phase change material candidate information library to obtain the heat dissipation requirements of various components of an auxiliary system; S3, extracting the structure and operation parameters of various components of the auxiliary system that affect the weight of the components, taking the structure and operation parameters of various components of the auxiliary system and the mass of the heat storage medium of the phase change heat storage material as optimization variables, establishing constraint conditions, and taking the total weight of the powertrain system as an objective function to construct an optimization model; S4, performing cyclic iterative optimization on the optimization model to obtain an optimal set, namely, a filling amount of the phase change material and the structure and operation parameters of various components of the auxiliary system; S5, selecting other phase change heat storage materials, repeating steps S2-S4, and obtaining an optimal set corresponding to the minimum total weight of the powertrain system.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle power systems and intelligent optimization methods, and in particular to an integrated design method for a power system cooling unit taking into account phase change heat storage. Background Art

[0002] The styling of automobiles is frequently updated, the configuration of the whole vehicle is constantly upgraded, and the space reserved for the engine in the cabin is limited. Therefore, higher requirements are placed on the overall layout of the engine. The pursuit of compactness and small appearance is a new trend in the concept and layout design of the engine. Traditional powertrain design generally uses the actual heat generated by the engine as the heat dissipation requirement of the auxiliary system components. When a high-power power unit is selected, the heat generation will be huge, which further causes the auxiliary system to select components with larger volume and weight to meet the required heat dissipation requirements. The overall powertrain is relatively large and bulky. In addition, conventional powertrain designs are mostly repeated verification and iteration directly on the engine, motor and auxiliary system, which is a large workload and easy to fall into local optimality.

[0003] The prior art discloses a new energy vehicle thermal management system using phase change energy storage technology, including an air cooler, an air conditioning evaporator, a power battery, a control system and a phase change energy storage box filled with phase change material, which are arranged in the body of the vehicle. The air cooler is connected to the phase change energy storage box through a working fluid pipeline filled with working fluid, and the working fluid pipeline passes through the air conditioning evaporator; a valve group is arranged on the working fluid pipeline, and the valve group, the air cooler and the air conditioning evaporator are connected to the control system. In winter, the heat in the air is stored in the phase change energy storage box through the air cooler, and the heat is used to heat the battery when the car is just started. When the car is running and the battery is heated, the excess heat is transferred to the floor of the car through the heat pipe, so that the temperature inside the car is increased to assist the air conditioning heating and reduce energy consumption; in summer nights, the heat with a lower temperature is stored in the phase change energy storage box. When the car is running, the cold in the phase change energy storage box is circulated to the battery and the air conditioning evaporator through the working fluid pipeline, so as to reduce the battery temperature and assist the air conditioning refrigeration.

[0004] The prior art discloses a multi-energy coupling system control optimization method based on an improved non-dominated genetic algorithm, which relates to the field of multi-energy coupling system control, including determining an objective function according to a simulation model of the multi-energy coupling system, and then obtaining an objective function space according to parent controlled variables and the objective function, sorting and ranking each parent controlled variable through a non-dominated genetic algorithm, and improving the non-dominated genetic algorithm by adding a mechanism for dynamically selecting the optimal solution, and also selecting different ways to generate child controlled variables according to the number of groups of parent controlled variables included in the highest level, so that after selecting the possible direction of the optimal solution of the objective function, the optimal solution is searched in the direction of the optimal solution, thereby accelerating the convergence speed and realizing real-time control of the multi-energy coupling system.

[0005] In summary, existing automotive thermal management methods mostly use additional special phase change heat storage devices to control heat loads, which poses great challenges to system space and layout. In addition, traditional design methods do not consider the impact of adding phase change materials and related devices on the total weight of the powertrain system, and lack relevant integrated optimization methods. Summary of the invention

[0006] The present invention proposes an integrated design method for a power system cooling unit taking phase change heat storage into account. During the engine manufacturing stage, a high thermal conductivity and flexible phase change heat storage medium is filled in the gaps around the outer walls of the cylinder block and the cylinder head, thereby reducing the maximum heat dissipation demand of the engine. The mass of the phase change heat storage material, the structural parameters of the radiator, intercooler, transmission oil radiator, and engine oil radiator in the auxiliary system, and system operating parameters such as temperature are used as optimization variables. The total weight of the powertrain is used as the objective function for cyclic iterative optimization. In this way, an optimal powertrain that takes phase change heat storage into account and meets both the heat dissipation demand and the weight demand can be provided at the design stage.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] An integrated design method for a power system cooling unit taking into account phase change heat storage comprises:

[0009] S1. Obtaining operating temperature information of the engine, selecting a number of phase change thermal storage materials based on the operating temperature information, and establishing a phase change material candidate information library;

[0010] S2, selecting one of the phase change thermal storage materials from the phase change material candidate information library, and calculating the actual heat dissipation demand of the engine after the peak heat load is suppressed by the phase change thermal storage material, that is, the heat dissipation demand of each component of the auxiliary system according to the thermophysical properties of the phase change thermal storage material and the engine power model;

[0011] S3. Based on the heat dissipation requirements, temperature transfer relationship and parameter coupling matching relationship of each component of the auxiliary system, an auxiliary system performance calculation model is established, and the structure and operation parameters of each component of the auxiliary system that affect the weight of the component are extracted from the auxiliary system performance calculation model. The structure and operation parameters of each component of the auxiliary system and the mass of the heat storage medium of the phase change thermal storage material are used as optimization variables, constraint conditions are established, and the total weight of the powertrain system is used as the objective function to construct an optimization model;

[0012] S4, performing cyclic iterative optimization on the optimization model, and when the number of iterations is reached, outputting the optimal solution set corresponding to the minimum total weight, that is, the optimal heat storage medium quality under the currently used phase change thermal storage material and the structure and operation parameters of each component of the auxiliary system;

[0013] S5. Select other phase change thermal storage materials from the phase change material candidate information library, and repeat steps S2-S4 until all phase change thermal storage materials in the phase change material candidate information library are completely traversed to obtain the phase change thermal storage material corresponding to the minimum total weight of the powertrain system, the filling amount of the phase change material, and the structure and operation parameters of each component of the auxiliary system.

[0014] Optionally, the temperature transfer relationship among the components of the auxiliary system includes: the transfer relationship among the engine water jacket outlet temperature, the high-temperature radiator coolant inlet temperature, the low-temperature radiator coolant outlet temperature, the oil radiator coolant inlet and outlet temperatures and the transmission oil radiator coolant inlet temperature.

[0015] Optionally, the method for obtaining the temperature transfer relationship of each component of the auxiliary system is:

[0016] T out.eng =T in.h ; T out.l =T in.oil ; T out.oil =T in.tr ;

[0017] Among them, T out.eng is the engine water jacket outlet temperature, T in.h is the high temperature radiator coolant inlet temperature, T out.l is the low temperature radiator coolant outlet temperature, T in.oil For the oil radiator coolant inlet, T out.oil is the outlet temperature, T in.tr is the coolant inlet temperature of the transmission oil radiator.

[0018] Optionally, obtaining the parameter coupling matching relationship of each component of the auxiliary system includes:

[0019] Cooling air flow rate:

[0020]

[0021] Among them, q v,a is the cooling air flow rate, Φ is the heat dissipation requirement of each component of the auxiliary system, Δt a is the temperature rise of cooling air entering and leaving the water radiator, ρ a is the density of air, c p,a is the constant pressure specific heat capacity of air;

[0022] Air volume required by the fan:

[0023]

[0024] Among them, q v,fan The air volume required by the fan, q v,ais the cooling air flow rate, η is the volumetric efficiency;

[0025] The circulating volume flow rate of the engine cooling water is the flow rate of the water pump:

[0026]

[0027] Among them, q v,w is the circulating volume flow rate of engine cooling water, q v,pump is the flow rate of the water pump, Φ is the heat dissipation requirement of each component of the auxiliary system, ρ w is the density of cooling water, c p,w is the constant pressure specific heat capacity of cooling water, Δt w The temperature of cooling water circulates in the cooling system.

[0028] Optionally, obtaining the parameter coupling matching relationship of each component of the auxiliary system further includes:

[0029] The relationship between the inner and outer diameters of the fan and the front area of ​​the radiator core:

[0030]

[0031] Where, π is the circumference of a circle, D2 is the outer diameter of the fan, D1 is the inner diameter of the fan, and F R is the positive area of ​​the radiator;

[0032] Fan outer diameter:

[0033]

[0034] Where D2 is the outer diameter of the fan, F R is the positive area of ​​the radiator;

[0035] The relationship between the static pressure of the fan and the pressure drop of the radiator:

[0036] p df =ΔP a +ΔP

[0037] Among them, p df is the relationship between the static pressure of the fan and the pressure drop of the radiator, ΔP a is the resistance of air passing through the radiator and intercooler, and ΔP is the air flow resistance excluding the radiator and intercooler.

[0038] Optionally, the auxiliary system performance calculation model includes: a radiator, an intercooler, an engine oil radiator, a transmission oil radiator, a cooling fan and a cooling water pump quality characterization model.

[0039] Optionally, the method for establishing the constraint condition is:

[0040]

[0041] Among them, st is a constraint condition, H1 is the cold / hot side wing height of the low-temperature radiator of the intercooler, H2 is the cold / hot side wing height of the low-temperature radiator of the high-temperature radiator, S1 is the cold / hot side pitch of the low-temperature radiator of the intercooler, S2 is the cold / hot side pitch of the low-temperature radiator of the high-temperature radiator, δ1 is the cold / hot side wing thickness of the low-temperature radiator of the intercooler, δ2 is the cold / hot side wing thickness of the low-temperature radiator of the high-temperature radiator, B1 is the effective width of the high-temperature radiator, B2 is the effective width of the low-temperature radiator core, B3 is the effective width of the intercooler core, B4 is the effective width of the engine oil radiator core, B5 is the effective width of the transmission oil radiator core, L1 is the effective length of the high-temperature radiator core, L2 is the effective length of the low-temperature radiator core, L3 is the effective length of the intercooler core, n b is the number of intercooler fin layers, q w is the cold side air flow, G 1.h is the mass flow rate of coolant on the hot side of the high temperature radiator, G 2.h is the mass flow rate of coolant on the hot side of the low temperature radiator, G 1.l is the air mass flow rate on the cold side of the high temperature radiator, G 2.l is the air mass flow rate on the cold side of the low temperature radiator, G co1 is the coolant mass flow rate on the cold side of the oil radiator, G co2 is the coolant mass flow rate on the cold side of the transmission oil radiator, G oil is the oil mass flow rate, G tr is the mass flow rate of transmission oil, P1 is the hot side of high / low temperature radiator, P2 is the cold side pressure of high / low temperature radiator, T out.l is the outlet temperature of the cold side of the low temperature radiator, ΔP I.air is the pressure drop on the charge air side of the intercooler, ΔP coolant is the pressure drop on the coolant side of the radiator, A s is the actual heat dissipation area, A x is the required heat dissipation area, l coolant is the length of the engine oil / transmission oil radiator coolant channel, l heat is the length of the hot fluid channel.

[0042] Optionally, the method for obtaining the total weight of the powertrain system is:

[0043] m 总 =f(H1,H2,S1,S2,δ1,δ2,B1,B2,B3,B4,B5,L1,L2,L3,

[0044] n b ,q w ,G 1.h ,G 2.h ,G 1.l ,G 2.l ,G co1 ,Gco2 ,G oil ,G tr ,P1,P2,T out.l ,m')

[0045] Among them, m 总 is the total weight of the powertrain system, H1 is the height of the cold / hot side wing of the intercooler low-temperature radiator, H2 is the height of the cold / hot side wing of the high-temperature radiator low-temperature radiator, S1 is the cold / hot side pitch of the intercooler low-temperature radiator, S2 is the cold / hot side pitch of the high-temperature radiator low-temperature radiator, δ1 is the cold / hot side wing thickness of the intercooler low-temperature radiator, δ2 is the cold / hot side wing thickness of the high-temperature radiator low-temperature radiator, B1 is the effective width of the high-temperature radiator, B2 is the effective width of the low-temperature radiator core, B3 is the effective width of the intercooler core, B4 is the effective width of the engine oil radiator core, B5 is the effective width of the transmission oil radiator core, L1 is the effective length of the high-temperature radiator core, L2 is the effective length of the low-temperature radiator core, L3 is the effective length of the intercooler core, n b is the number of intercooler fin layers, q w is the cold side air flow, G 1.h is the mass flow rate of coolant on the hot side of the high temperature radiator, G 2.h is the mass flow rate of coolant on the hot side of the low temperature radiator, G 1.l is the air mass flow rate on the cold side of the high temperature radiator, G 2.l is the air mass flow rate on the cold side of the low temperature radiator, G co1 is the coolant mass flow rate on the cold side of the oil radiator, G co2 is the coolant mass flow rate on the cold side of the transmission oil radiator, G oil is the oil mass flow rate, G tr is the mass flow rate of transmission oil, P1 is the hot side of high / low temperature radiator, P2 is the cold side pressure of high / low temperature radiator, T out.l is the outlet temperature of the cold side of the low-temperature radiator, and m' is the filling amount of the phase change thermal storage material.

[0046] The beneficial effects of the present invention are:

[0047] The present invention fills the gaps outside the engine cylinder block and cylinder head with flexible phase change materials with high thermal conductivity and high latent heat. In order to ensure that liquid leakage does not occur after the phase change of the phase change material, the phase change material is stored in the form of microcapsules. The use of the engine's own gaps for phase change heat storage also avoids increasing the space occupied by the powertrain to a certain extent. The phase change material absorbs the heat transferred by the cylinder block and cylinder head, weakens the peak heat generation, reduces the heat load of the auxiliary system, and is conducive to miniaturization and lightweighting of the auxiliary system. At the same time, the constant temperature of the phase change process is used to reduce the peak heat load of the engine to avoid overheating of the engine body affecting performance.

[0048] The present invention fills the gaps of the engine with phase change materials, which increases the weight of the engine body, but at the same time reduces the heat load of the auxiliary system, thereby reducing the design weight of the auxiliary system. By establishing a powertrain integrated design method that takes phase change heat storage into account, the weight of the engine body and the weight of the auxiliary system are calculated as a whole, and the total weight is used as the objective function. The filling amount of the phase change material and the structure and operating parameters of the auxiliary system are used as optimization variables. The heuristic optimization algorithm is used to perform cyclic iteration optimization to obtain the best optimization variable parameter combination for total weight optimization. Based on this method, different phase change materials are traversed to complete the optimal selection.

[0049] The present invention writes the entire design process into a program through programming software, which can complete all the above-mentioned optimization iterations and selection processes in one click, greatly reducing manual workload, avoiding repeated experiments, and reducing design costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 A logic diagram of an integrated design method for a power system cooling unit taking into account phase change heat storage according to an embodiment of the present invention;

[0052] Figure 2 It is a schematic diagram of an integrated design model of a powertrain module and a heat storage module according to an embodiment of the present invention;

[0053] Figure 3 Schematic diagram of heat storage and release of phase change material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] This embodiment designs an integrated design method for a power system cooling unit taking into account phase change heat storage, and the heat load is regulated in the form of filling the gaps outside the engine cylinder block and the cylinder head with phase change heat storage materials. When the vehicle is running in a high-power operating condition, the peak heat load of the engine is reduced by the phase change heat storage material to reduce the heat dissipation demand of the auxiliary system. In the low-power operating condition, the heat stored in the phase change material is released by the cooling system, thereby stabilizing the working environment temperature of the engine and preventing overheating, so as to achieve the goal of reducing the peak heat load without occupying additional space. The auxiliary system is optimized for the new heat load to reduce the weight of the auxiliary system, but at the same time, because filling the phase change material will increase the weight of the engine body, it is necessary to make a comprehensive consideration of the total weight of the powertrain. By establishing a coupled calculation model of the powertrain module and the heat storage material, taking the total weight of the powertrain as the objective function, and taking the filling amount of the phase change material and the auxiliary system structure and operating parameters as the optimization variables, the heuristic optimization algorithm is combined to perform cyclic iterative optimization within a certain range, and at the same time, the best optimization variable parameter combination for total weight optimization is obtained to avoid repeated experiments and falling into the local optimum.

[0057] like Figure 1 As shown, the present embodiment discloses an integrated design method for a power system cooling unit taking into account phase change heat storage, including: S1, obtaining the operating temperature information of the engine, selecting a plurality of phase change heat storage materials based on the operating temperature information, and establishing a phase change material candidate information library; S2, selecting one of the phase change heat storage materials from the phase change material candidate information library, and obtaining the actual heat dissipation demand of the engine after the peak heat load is suppressed by the phase change heat storage material according to the thermophysical properties of the phase change heat storage material and the engine power model coupling calculation, that is, the heat dissipation demand of each component of the auxiliary system; S3, establishing an auxiliary system performance calculation model based on the heat dissipation demand, temperature transfer relationship and parameter coupling matching relationship of each component of the auxiliary system, and extracting the structure and operation of each component of the auxiliary system that affects the weight of the component from the auxiliary system performance calculation model. S4, perform iterative optimization on the optimization model, and when the number of iterations is reached, output the optimal solution set corresponding to the minimum total weight, that is, the optimal quality of the heat storage medium under the phase change thermal storage material currently used and the structure and operation parameters of the auxiliary system components; S5, select other phase change thermal storage materials from the phase change material candidate information library, repeat steps S2-S4, until all phase change thermal storage materials in the phase change material candidate information library are completely traversed, and the phase change thermal storage materials corresponding to the minimum total weight of the powertrain system, the filling amount of the phase change material, and the structure and operation parameters of the auxiliary system components are obtained.

[0058] The present invention proposes an integrated design method for a power system cooling unit taking phase change heat storage into account. By establishing a coupled calculation model of the powertrain module and the heat storage material, the mass of the phase change heat storage material, the structural parameters of the radiator, intercooler, transmission oil radiator, and engine oil radiator in the auxiliary system, and the system operating parameters such as temperature are used as optimization variables, and the total weight of the powertrain is used as the objective function. A heuristic algorithm is used to perform single-objective optimization to find the best combination of optimization parameters. This solves the problems of the powertrain design being too cumbersome due to the high power demand in the traditional design and development stage, and the large workload caused by repeated iterative changes in calculations, and the easy fall into local optimality.

[0059] The integrated design method of powertrain considering phase change heat storage is as follows: Figure 1 As shown, the calculation logic illustrates that: the present invention takes the minimum total weight of the powertrain system as the optimization goal;

[0060] Based on the above objectives and definitions, a powertrain coupling design method considering phase change heat storage is established, such as Figure 1 As shown, it includes the following steps:

[0061] 1. Use the engine model database to select and match the engine. The specific steps are as follows:

[0062] 1.1. Obtain the operating parameter values ​​of the power unit based on the information input from the actual working conditions, and select the appropriate engine type and model from the engine model library through the performance efficiency curve;

[0063] 1.2. Use Simulink to build an engine average model, input the operating parameters into the engine average model, and obtain the engine speed, torque and power values.

[0064] 2. Select appropriate phase change thermal storage materials with high thermal conductivity and high latent heat according to the engine operating temperature information, obtain the material's phase change latent heat value and other thermal property information by looking up the table, and establish a phase change material candidate information database.

[0065] Selecting a suitable phase change thermal storage material with high thermal conductivity and high latent heat according to the engine operating temperature information includes: the phase change temperature of the phase change thermal storage material should be within the appropriate operating temperature range of the engine, and according to this principle, selecting a phase change thermal storage material with medium to high thermal conductivity and high latent heat that meets the conditions.

[0066] 3. Select a phase change thermal storage material from the candidate library, and calculate the heat dissipation requirements of each component of the auxiliary system after the phase change thermal storage material suppresses the peak heat load based on the coupling calculation of the thermal properties of the phase change thermal storage material and the engine power model, and further obtain the heat dissipation requirements of each component of the auxiliary system.

[0067] The calculation based on the coupling of the thermal properties of the phase change thermal storage material and the engine power model includes: originally without the phase change material, when the engine power is high, after the cooling water maintains the engine temperature at an appropriate temperature, its outlet temperature is 90°C. After adding the phase change thermal storage material, due to the temperature-invariant characteristic of the phase change material during the phase change process, that is, it maintains a constant temperature while absorbing heat, the outlet temperature of the cooling water from the engine water jacket is not as high as before, and the outlet temperature is about 80°C. For the radiator, the cooling water was previously reduced from 90°C to 75°C, and now it is reduced from 80°C to 75°C, so its heat dissipation demand can be said to have decreased.

[0068] Obtaining the actual heat dissipation requirements includes: the heat dissipation requirements of the water radiator need to be calculated based on the inlet and outlet temperatures of the coolant in the engine water jacket after the phase change material is added; similarly, the transmission oil radiator, engine oil radiator and other heat dissipation components are determined based on the inlet and outlet temperatures of their flowing media.

[0069] 4. According to the heat dissipation requirements, temperature transfer relationship and parameter coupling matching relationship between components, establish the auxiliary system performance calculation model, as shown in the attached Figure 2 As shown, the mass characterization models of the radiator, intercooler, oil radiator, transmission oil radiator, cooling fan and cooling water pump are included, and the structural and operating parameters of the auxiliary system components that affect the weight of the components and the heat storage medium mass of the phase change thermal storage material are extracted. These parameters are used as optimization variables, the total weight of the powertrain system is used as the objective function, and the working conditions, efficiency, pressure drop and other parameters of the vehicle power auxiliary system components are used as constraints to establish an optimization model.

[0070] Total weight of powertrain system m 总 :

[0071] m 总 =f(H1,H2,S1,S2,δ1,δ2,B1,B2,B3,B4,B5,L1,L2,L3,

[0072] n b ,q w ,G 1.h ,G 2.h ,G 1.l ,G 2.l ,G co1 ,G co2 ,G oil ,G tr ,P1,P2,T out.l ,m')

[0073] In the above formula, the meaning of each letter is as follows: H1, H2 is the wing height of the intercooler, high temperature radiator, low temperature radiator cold and hot side, m, S1, S2 is the pitch of the intercooler, high temperature radiator, low temperature radiator cold and hot side, m, δ1, δ2 is the wing thickness of the intercooler, high temperature radiator, low temperature radiator cold and hot side, m, B1, B2 is the effective width of the high temperature radiator and low temperature radiator core, m, B3 is the effective width of the intercooler core, m, B4, B5 is the effective width of the engine oil radiator and transmission oil radiator core, m, L1, L2 is the effective length of the high temperature radiator and low temperature radiator core, m, L3 is the effective length of the intercooler core, m, n b is the number of intercooler fin layers, q w is the cold side air flow, kg / s, G 1.h ,G 2.h is the mass flow rate of the coolant on the hot side of the high-temperature radiator and the low-temperature radiator, kg / m 2 ·s,G 1.l ,G 2.l is the air mass flow rate on the cold side of the high-temperature radiator and the low-temperature radiator, kg / m 2 ·s,G co1 ,G co2 is the coolant mass flow rate of the cold side of the oil radiator and transmission oil radiator, kg / m 2 ·s,G oil ,G tr is the mass flow rate of engine oil and transmission oil, kg / m 2 ·s, P1, P2 are the hot side and cold side pressures of high / low temperature radiators, MPa, T out.l is the outlet temperature of the cold side of the low-temperature radiator, and m' is the filling amount of the phase change thermal storage material.

[0074] Optimization goal:

[0075] Constraints:

[0076] In the above constraints, ΔP I.air Indicates the pressure drop on the charge air side of the intercooler, kPa; ΔP coolant Indicates the pressure drop on the coolant side of the radiator, kPa; A s ,A x Respectively represent the actual heat dissipation area and the required heat dissipation area; l coolant , l heat They represent the coolant channel length and the thermal fluid channel length of the engine oil / transmission oil radiator respectively.

[0077] In the auxiliary system design, the radiator, intercooler, oil radiator, and transmission oil radiator establish temperature transfer relationships and circulation loop flow information through the flow of coolant. The fan's air volume, static pressure, outer diameter, and water pump flow are all matched according to the radiator and intercooler design requirements.

[0078] Engine water jacket outlet temperature T out.eng , high temperature radiator coolant inlet temperature T in.h , low temperature radiator coolant outlet temperature T out.l , Oil radiator coolant inlet T in.oil , outlet temperature T out.oil , Transmission oil radiator coolant inlet temperature T in.tr The transitive relationship between them:

[0079] T out.eng =T in.h ; T out.l =T in.oil ; T out.oil =T in.tr ;

[0080] The flow rate of cooling air is determined by the heat balance equation according to the heat dissipation requirements of the cooling system, namely:

[0081]

[0082] In the formula, Δt a Indicates the temperature rise of cooling air inlet and outlet of water radiator, ℃, generally within 30~50℃, ρ a Indicates the density of air, kg / m 3 ;c p,a It represents the specific heat capacity of air at constant pressure, kJ / (kg·℃).

[0083] The air volume that the fan needs to provide is determined by the volumetric efficiency of the cooling air entering the radiator at the fan outlet, that is:

[0084]

[0085] In the formula, η represents volumetric efficiency, which is generally 0.8-0.9.

[0086] Similarly, the circulating volume flow rate of the engine cooling water, i.e. the flow rate of the water pump, is also calculated by the heat balance equation based on the heat dissipation demand Φ of the cooling system, namely:

[0087]

[0088] In the formula, ρ w Indicates the density of cooling water, kg / m 3 ;c p,wIndicates the constant pressure specific heat capacity of cooling water, kJ / (kg·℃); Δt w It indicates the temperature drop of cooling water in the cooling system, ℃. Generally, for a closed forced circulation water system, Δt w The value is between 5 and 12°C.

[0089] The relationship between the inner and outer diameters of the fan and the front area of ​​the radiator core is:

[0090]

[0091] According to the above formula, the outer diameter of the fan can be calculated as:

[0092]

[0093] In the above formula, D1 is the inner diameter of the fan, m; D2 is the outer diameter of the fan, m; F R is the positive area of ​​the radiator, m2; according to the above formula, the fan outer diameter coefficient is 0.79-0.93.

[0094] The relationship between the fan's static pressure and the radiator's pressure drop is:

[0095] p df =ΔP a +ΔP

[0096] In the formula, ΔP a is the resistance of air passing through the radiator and intercooler, Pa; ΔP is the resistance of the air flow path excluding the radiator and intercooler, generally 0.4~1.1ΔP a .

[0097] 5. Perform iterative optimization through a heuristic algorithm. When the number of iterations is reached, output the optimal solution set corresponding to the minimum total weight, that is, the optimal phase change material filling amount and auxiliary system structure and operating parameters under the currently used phase change material type, and record the results.

[0098] 6. Repeat steps 3-5 until all phase change material types in the candidate library are completely traversed.

[0099] 7. Obtain the optimal solution corresponding to the minimum total weight, that is, the optimal phase change material type, phase change material filling amount, auxiliary system component structure and operating parameters.

[0100] Phase change thermal storage material regulates heat load mechanism Figure 3Taking the example shown in the figure, the original cooling system needs to be designed based on the worst operating point of the engine thermal load (500kW). The phase change heat storage material filled in the gaps around the engine block and the cylinder head can be used to weaken the peak thermal load of the thermal engine by utilizing its phase change constant temperature heat absorption characteristics, so that its heat dissipation demand is reduced to 400kW. The cooling system is designed based on the optimized heat dissipation demand, and the space and weight occupied by the components can be greatly optimized, which can better meet the needs of miniaturization and lightweight. When the engine is working at a lower power or idle, the heat load is small (325kW), and the cooling system is used for cooling and cooling, so that the phase change material releases the stored heat and returns to a solid state, so as to achieve recycling to meet the actual dynamic working conditions.

[0101] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An integrated design method for a power system cooling unit taking into account phase change heat storage, characterized in that: include: S1. Obtaining operating temperature information of the engine, selecting a number of phase change thermal storage materials based on the operating temperature information, and establishing a phase change material candidate information library; S2, selecting one of the phase change thermal storage materials from the phase change material candidate information library, and calculating the actual heat dissipation demand of the engine after the peak heat load is suppressed by the phase change thermal storage material, that is, the heat dissipation demand of each component of the auxiliary system according to the thermophysical properties of the phase change thermal storage material and the engine power model; S3. Based on the heat dissipation requirements, temperature transfer relationship and parameter coupling matching relationship of each component of the auxiliary system, an auxiliary system performance calculation model is established, and the structure and operation parameters of each component of the auxiliary system that affect the weight of the component are extracted from the auxiliary system performance calculation model. The structure and operation parameters of each component of the auxiliary system and the mass of the heat storage medium of the phase change thermal storage material are used as optimization variables, constraint conditions are established, and the total weight of the powertrain system is used as the objective function to construct an optimization model; S4, performing cyclic iterative optimization on the optimization model, and when the number of iterations is reached, outputting the optimal solution set corresponding to the minimum total weight, that is, the optimal heat storage medium quality under the currently used phase change thermal storage material and the structure and operation parameters of each component of the auxiliary system; S5. Select other phase change thermal storage materials from the phase change material candidate information library, and repeat steps S2-S4 until all phase change thermal storage materials in the phase change material candidate information library are completely traversed to obtain the phase change thermal storage material corresponding to the minimum total weight of the powertrain system, the filling amount of the phase change material, and the structure and operation parameters of each component of the auxiliary system.

2. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 1, characterized in that: The temperature transfer relationship of the auxiliary system components includes: the transfer relationship between the engine water jacket outlet temperature, the high-temperature radiator coolant inlet temperature, the low-temperature radiator coolant outlet temperature, the oil radiator coolant inlet and outlet temperatures and the transmission oil radiator coolant inlet temperature.

3. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 1, characterized in that: The method for obtaining the temperature transfer relationship of each component of the auxiliary system is: T out.eng =T in.h ;T out.l =T in.oil ;T out.oil =T in.tr ; Among them, T out.eng is the engine water jacket outlet temperature, T in.h is the high temperature radiator coolant inlet temperature, T out.l is the low temperature radiator coolant outlet temperature, T in.oil For the oil radiator coolant inlet, T out.oil is the outlet temperature, T in.tr is the coolant inlet temperature of the transmission oil radiator.

4. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 1, characterized in that: Acquiring the parameter coupling matching relationship of each component of the auxiliary system includes: Cooling air flow rate: Among them, q v,a is the cooling air flow rate, Φ is the heat dissipation requirement of each component of the auxiliary system, Δt a is the temperature rise of cooling air entering and leaving the water radiator, ρ a is the density of air, c p,a is the constant pressure specific heat capacity of air; Air volume required by the fan: Among them, q v,fan The air volume required by the fan, q v,a is the cooling air flow rate, η is the volumetric efficiency; The circulating volume flow rate of the engine cooling water is the flow rate of the water pump: Among them, q v,w is the circulating volume flow rate of engine cooling water, q v,pump is the flow rate of the water pump, Φ is the heat dissipation requirement of each component of the auxiliary system, ρ w is the density of cooling water, c p,w is the constant pressure specific heat capacity of cooling water, Δt w The temperature of cooling water circulates in the cooling system.

5. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 4, characterized in that: Acquiring the parameter coupling matching relationship of each component of the auxiliary system also includes: The relationship between the inner and outer diameters of the fan and the front area of ​​the radiator core: Where, π is the circumference of a circle, D2 is the outer diameter of the fan, D1 is the inner diameter of the fan, and F R is the positive area of ​​the radiator; Fan outer diameter: Where D2 is the outer diameter of the fan, F R is the positive area of ​​the radiator; The relationship between the static pressure of the fan and the pressure drop of the radiator: p df =ΔP a +ΔP Among them, p df is the relationship between the static pressure of the fan and the pressure drop of the radiator, ΔP a is the resistance of air passing through the radiator and intercooler, and ΔP is the air flow resistance excluding the radiator and intercooler.

6. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 4, characterized in that: The auxiliary system performance calculation model includes: a radiator, an intercooler, an engine oil radiator, a transmission oil radiator, a cooling fan and a cooling water pump quality characterization model.

7. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 1, characterized in that: The method of establishing the constraint condition is: Among them, st is a constraint condition, H1 is the cold / hot side wing height of the low-temperature radiator of the intercooler, H2 is the cold / hot side wing height of the low-temperature radiator of the high-temperature radiator, S1 is the cold / hot side pitch of the low-temperature radiator of the intercooler, S2 is the cold / hot side pitch of the low-temperature radiator of the high-temperature radiator, δ1 is the cold / hot side wing thickness of the low-temperature radiator of the intercooler, δ2 is the cold / hot side wing thickness of the low-temperature radiator of the high-temperature radiator, B1 is the effective width of the high-temperature radiator, B2 is the effective width of the low-temperature radiator core, B3 is the effective width of the intercooler core, B4 is the effective width of the engine oil radiator core, B5 is the effective width of the transmission oil radiator core, L1 is the effective length of the high-temperature radiator core, L2 is the effective length of the low-temperature radiator core, L3 is the effective length of the intercooler core, n b is the number of intercooler fin layers, q w is the cold side air flow, G 1.h is the mass flow rate of coolant on the hot side of the high temperature radiator, G 2.h is the mass flow rate of coolant on the hot side of the low temperature radiator, G 1.l is the air mass flow rate on the cold side of the high temperature radiator, G 2.l is the air mass flow rate on the cold side of the low temperature radiator, G co1 is the coolant mass flow rate on the cold side of the oil radiator, G co2 is the coolant mass flow rate on the cold side of the transmission oil radiator, G oil is the oil mass flow rate, G tr is the mass flow rate of transmission oil, P1 is the hot side of high / low temperature radiator, P2 is the cold side pressure of high / low temperature radiator, T out.l is the outlet temperature of the cold side of the low temperature radiator, ΔP I.air is the pressure drop on the charge air side of the intercooler, ΔP coolant is the pressure drop on the coolant side of the radiator, A s is the actual heat dissipation area, A x is the required heat dissipation area, l coolant is the length of the engine oil / transmission oil radiator coolant channel, l heat is the length of the hot fluid channel.

8. The integrated design method of a power system cooling unit taking into account phase change heat storage according to claim 1, characterized in that: The method for obtaining the total weight of the powertrain system is: <h2 style=";text-align:left;direction:ltr">m<h2 style=";text-align:left;direction:ltr"> 总 <h2 style=";text-align:left;direction:ltr"> =f(H1,H2,S1,S2,δ1,δ2,B1,B2,B3,B4,B5,L1,L2,L3, n b ,q w ,G 1.h ,G 2.h ,G 1.l ,G 2.l ,G co1 ,G co2 ,G oil ,G tr ,P1,P2,T out.l ,m') Among them, m 总 is the total weight of the powertrain system, H1 is the height of the cold / hot side wing of the intercooler low-temperature radiator, H2 is the height of the cold / hot side wing of the high-temperature radiator low-temperature radiator, S1 is the cold / hot side pitch of the intercooler low-temperature radiator, S2 is the cold / hot side pitch of the high-temperature radiator low-temperature radiator, δ1 is the cold / hot side wing thickness of the intercooler low-temperature radiator, δ2 is the cold / hot side wing thickness of the high-temperature radiator low-temperature radiator, B1 is the effective width of the high-temperature radiator, B2 is the effective width of the low-temperature radiator core, B3 is the effective width of the intercooler core, B4 is the effective width of the engine oil radiator core, B5 is the effective width of the transmission oil radiator core, L1 is the effective length of the high-temperature radiator core, L2 is the effective length of the low-temperature radiator core, L3 is the effective length of the intercooler core, n b is the number of intercooler fin layers, q w is the cold side air flow, G 1.h is the mass flow rate of coolant on the hot side of the high temperature radiator, G 2.h is the mass flow rate of coolant on the hot side of the low temperature radiator, G 1.l is the air mass flow rate on the cold side of the high temperature radiator, G 2.l is the air mass flow rate on the cold side of the low temperature radiator, G co1 is the coolant mass flow rate on the cold side of the oil radiator, G co2 is the coolant mass flow rate on the cold side of the transmission oil radiator, G oil is the oil mass flow rate, G tr is the mass flow rate of transmission oil, P1 is the hot side of high / low temperature radiator, P2 is the cold side pressure of high / low temperature radiator, T out.l is the outlet temperature of the cold side of the low-temperature radiator, and m' is the filling amount of the phase change thermal storage material.

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