附件

电动汽车动力电池相变控温系统设计

学院（系）： 国际教育学院

专业班级： 车辆工程gj1402

学生姓名： 吴秦凯

指导教师： 谭罡风

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Abstract: As the power source of electric vehicles, the power battery has a direct impact on various attribute parameters of the electric vehicle. Among them, the operating temperature of the power battery has a great influence on the performance of the battery. Therefore, it is necessary to design the battery thermal management system. The heat pipe is a new type of heat transfer element that realizes heat transfer by its internal working liquid phase transition, and has high thermal conductivity and excellent isothermality. The design of the thermal management system of the battery adopts the heat pipe technology to quickly and effectively conduct the heat generated inside the battery and achieve a good heat transfer effect so as to ensure that the battery operates at an appropriate temperature. This paper mainly studies the heat dissipation of single cells using heat pipe technology under 1C discharge condition. The corresponding heat pipes are designed and the heat dissipation calculations are performed for selected batteries. The heat pipe heat dissipation system designed by the design is verified and calculated. The research results show that the designed fin heat pipe cooling system can meet the proposed heat dissipation requirements.

Key words Electric vehicle Battery thermal management Lithium battery Phase change Material heat pipe Heat dissipation

Catalog

1 Introduction 1

1.1 Research Background and Significance 1

1.2 Battery Thermal Management Overview 3

1.3 Current Status of Battery Thermal Management 7

1.3.1 Research Status of Air-cooled Heat Dissipation 7

1.3.2 Research Status of Liquid Cooled Heat Dissipation 8

1.3.3 Status of Research on Thermal Dissipation of Phase Change Materials 9

1.4 Heat Pipe Introduction 10

1.4.1 Working Principles and Features of Heat Pipes 10

1.4.2 Development of Heat Pipes 12

1.4.3 Heat Pipe Classification and Application 14

1.4.4 Status of Heat Pipe Applications 15

1.5 Classification and Characteristics of Fin Heat Pipes 18

1.5.1 Straight fins 19

1.5.2 Wavy fins 20

1.5.3 Slotted fins 21

1.6 Main research content 22

2. Calculation of the battery 23

2.1 Battery Selection 23

2.2 Motor Selection 24

2.3 Determination of Battery Arrangement 25

2.3.1 Determination of Parallel Connection of Battery Strings 25

2.3.2 Grouping 25

2.3.3 Basic parameters of the battery pack 25

2.4 Summary of this chapter 26

3. Heat pipe design 27

3.1 Heat management theory 27

3.1.2 Capillary pressure and maximum length of heat pipe 27

3.2 heat pipe heat transfer limit 32

3.2.1 Limit Accounting Formula 34

3.3 Heat Pipe Type 36

3.3.1 Two-phase Closed Thermosyphon 36

3.3.2 Rotary (slewing) heat pipe 38

3.3.3 Separate Heat Pipe 40

3.4.1 Selection of working fluid 48

3.4.2 Selection of wick 50

3.4.3 Selection of Shell Materials 50

3.4.4 Specific Heat Pipe Design 51

3.5 Summary of this chapter 58

4. Design of fins 59

4.1 Selection of fins and materials 59

4.2 Selection of specific fin parameters 59

4.3 Determination of the number of fins 60

4.4 Heat Dissipation Check 60

4.5 Summary of this chapter 60

5. Heat calculation 62

5.1 Lithium iron phosphate battery heat generation mechanism 62

5.2 lithium iron phosphate battery heat transfer characteristics 63

5.3 heat transfer process 64

5.3.1 Heat Transfer of Batteries and Heat Pipes 64

5.3.2 heat transfer inside the heat pipe 64

5.3.3 Heat dissipation of fins 65

5.4 Specific calculations. 65

5.4.1 Calculation of Heat Production by Single Cell. 65

5.4.2 Copper Surface Heat Transfer Calculation 65

5.4.3 Fin Heat Calculation 65

5.5 Summary of this chapter 66

6. Summary 67

6.1 full text summary 67

6.2 Outlook 68

7. References 69

1 Introduction

1.1 Research Background and Significance

With the rapid development of the national economy and the continuous progress of society, the level of material life of the general public has been continuously improved. At the same time as the main mode of transportation for people - the rapid development of automobiles, the rapid development of the automotive industry has driven the continuous advancement of automotive technology, and the automotive brand. And the annual output of automobiles also keeps refreshing historical records. The energy shortage caused by intensified automobile energy consumption and the environmental problems caused by tail gas emissions have become more serious. According to statistics, in the decade from 2003 to 2013, China’s annual oil consumption exceeded 300 million tons, and exceeded 500 million tons for the first time in 2013, of which the proportion of the transportation industry as an energy-consuming industry reached 30%. -35%. In addition, the greenhouse gas emissions caused by the energy consumption of the transportation industry accounted for 28% of the total. In recent years, smog days have frequently appeared in major cities, and the PM2.5 index has remained high. The exhaust of automobile emissions has become the target of air pollution. Under the dual pressures of energy and the environment, the dual advantages of energy-saving and new energy vehicles in terms of energy saving and emission reduction have made it a new development direction for governments in various countries to increase support and major automotive groups to increase research funding. Energy-saving and new energy vehicles are one of the effective ways of energy conservation and emission reduction in the transportation sector. They are one of the seven strategic emerging industries in China and one of the ten key areas for promotion in the “Made in China 2025”. Energy-saving and new energy vehicles will become vehicles. The outbreak of technological innovation will also become a new focus for the development of China's auto industry.

The innovation of energy-saving and new energy vehicles is reflected in the power system, which includes both the improvement of traditional power and the development of new energy power. As the core power components of hybrid and electric vehicles, the power battery directly determines the performance of the new energy vehicle, not only restricts its development from scientific research to industrialization, but also determines the market price of new energy vehicles. At present, the impediment to the development of the power battery technology is that the power battery has low energy density, short cycle life, high reliability and safety due to temperature, and high cost resulting from this, and it is difficult to achieve breakthroughs in battery technology. How to maximize the use of battery performance, reasonable distribution of battery power, reduce the impact of temperature caused by the use of the process is particularly important.