清华大学医学院生物医学工程系教授,中国科学院理化技术研究所研究员。先后入选中国科学院及清华大学百人计划,国家杰出青年科学基金获得者。长期从事液态金属、生物医学工程与工程热物理等领域交叉科学问题研究并作出系列开创性贡献。发现液态金属诸多全新科学现象、基础效应和变革性应用途径,开辟了液态金属在生物医疗、柔性机器人、印刷电子、3D打印、先进能源以及芯片冷却等领域突破性应用,成果在世界范围产生广泛影响出版14部跨学科前沿著作及20篇应邀著作章节;发表期刊论文480余篇(20余篇英文封面或封底故事);申报发明专利200余项,已获授权130余项。曾获国际传热界最高奖之一The William Begell Medal、全国首届创新争先奖、中国制冷学会技术发明一等奖、ASME会刊Journal of Electronic Packaging年度唯一最佳论文奖、入围及入选两院院士评选中国十大科技进展新闻各1次,入选CCTV 2015年度十大科技创新人物等。
目錄:
Chapter 1Introduction1
1.1Increasing Challenges in Advanced Cooling2
1.2Water Cooling and New Alternatives4
1.3Basic Features of Conventional Heat Exchangers6
1.3.1Heat Exchanger Classification by Geometry and
Structure7
1.3.2Heat Exchange Enhancement Techniques12
1.4Limitations of Waterbased Heat Exchanger13
1.4.1Overall Properties of Water13
1.4.2Adhesion and Cohesion14
1.4.3Surface Tension14
1.4.4Specific Heat14
1.4.5Conductivity15
1.5Liquid Metal Coolant for Chip Cooling15
1.6Some Facts about Liquid Metal17
1.7Revisit of Traditional Liquid Metal Cooling19
1.8Liquid Metal Enabled Innovation on Conventional
Heat Exchanger22
1.9Potential Application Areas of Liquid Metal Thermal
Management 23
1.9.1Chip Cooling23
1.9.2Heat Recovery25
1.9.3Energy System27
1.9.4Heat Transfer Process Engineering28
1.9.5Aerospace Exploration28
1.9.6Appliances in Large Power Systems29
1.9.7Thermal Interface Material29
1.9.8More New Conceptual Applications31
1.10Technical and Scientific Challenges in Liquid Metal
Heat Transfer 32
1.11Conclusion35
References36
Chapter 2Typical Liquid Metal Medium and Properties for Advanced
Cooling44
2.1Typical Properties of Liquid Metals45
2.1.1Low Melting Point45
2.1.2Thermal Conductivity45
2.1.3Surface Tension48
2.1.4Heat Capacity49
2.1.5Boiling Temperature50
2.1.6Subcooling Point50
2.1.7Viscosity51
2.1.8Electrical Properties52
2.1.9Magnetic Properties52
2.1.10Chemical Properties52
2.2Alloy Candidates with Low Melting Point53
2.2.1Overview53
2.2.2GaIn Alloy53
2.2.3NaK Alloy55
2.2.4Woods Metal55
2.3Nano Liquid Metal as More Conductive Coolant or Grease55
2.3.1Technical Concept of Nano Liquid Metal55
2.3.2Performance of Typical Nano Liquid Metals56
2.4Liquid Metal Genome towards New Material Discovery61
2.4.1About Liquid Metal Material Genome61
2.4.2Urgent Needs on New Liquid Metals62
2.4.3Category of Room Temperature Liquid Metal Genome62
2.5Fundamental Routes toward Finding New Liquid Metal Materials64
2.5.1Alloying Strategy from Single Metal Element64
2.5.2Making Composite from Binary Liquid Alloys65
2.5.3Realizing Composite from Multicomponent Liquid Alloys66
2.5.4Nano Technological Strategies66
2.5.5Additional Physical Approaches66
2.5.6Chemical Strategies67
2.6Fundamental Theories for Material Discovery68
2.6.1Calculation of Phase Diagram (CALPHAD)68
2.6.2First Principle Prediction69
2.6.3Molecular Dynamics Simulation69
2.6.4Other Theoretical Methods70
2.7Experimental Ways for Material Discovery70
2.8Theoretical and Technical Challenges71
2.9Conclusion73
References73Chapter 3Fabrications and Characterizations of Liquid Metal Cooling
Materials80
3.1Preparation Methods81
3.1.1Alloying81
3.1.2Oxidizing81
3.1.3Fabrication of Liquid Metal Droplets82
3.1.4Preparation of Liquid Metal Nano Particles83
3.1.5Coating of Liquid Metal Surface84
3.1.6Loading with Nano Materials86
3.1.7Compositing with Other Materials87
3.2Characterizations of Functional Liquid Metal Materials87
3.2.1Regulation of Thermal Properties88
3.2.2Regulation of Electrical Properties88
3.2.3Regulation of Magnetic Properties89
3.2.4Regulation of Fluidic Properties89
3.2.5Regulation of Chemical Properties89
3.3Liquid Metal as Energy Harvesting or Conversion Medium90
3.4Low Temperature Liquid Metal Used in Harsh Environment91
3.4.1Working of Liquid Metal under Cryogenic Situation91
3.4.2Basics about Cryogenic Cooling92
3.5Potential Metal Candidates with Melting Point below Zero
Centigrade 94
3.5.1Mercury95
3.5.2Particularities of Gallium or Its alloys96
3.5.3Alkali Metal and Its Alloys97
3.6Ways to Make Low Temperature Liquid Metal100
3.6.1Phase Diagram Calculation101
3.6.2Subcooling of Metal Melt102
3.6.3Experimental Approaches104
3.7Potential Roles for Future Low Temperature Liquid Metal105
3.8Conclusion107
References107Chapter 4Corrosion Issues in Liquid Metalbased Thermal Management114
4.1Corrosions Caused by Liquid Metal on Specific Substrates115
4.2Characterization of Liquid Metal Corrosion116
4.3Corrosion Trends of Typical Substrates with Liquid Gallium117
4.4Microscopic SEMEDS Observation and Analysis119
4.4.1SEM Quantification of Corroded Surface119
4.4.2EDS Quantification of Corroded Surface120
4.4.3EDS Quantification of Corroded Crosssection123
4.5Factors Affecting the Liquid Metal Corrosion124
4.6Anticorrosion of Liquid Metal on Substrate126
4.7Quantification of Gallium Alloy on AOA128
4.7.1Thermal Transfer Simulation and Setting of Anodized
Aluminum Alloy128
4.7.2Thermal Transfer Performance130
4.7.3Corrosion Resistance of Anodized Aluminum Alloy131
4.8Conclusion132
References133Chapter 5Nano Liquid Metal towards Making Enhanced Materials135
5.1Typical Features of Nano Liquid Metals136
5.2Application Issues of Nano Liquid Metals137
5.2.1Energy Management137
5.2.2Energy Conversion138
5.2.3Energy Storage139
5.2.4Interactions between Liquid Metal and Micronano
Particles140
5.2.5Fabrication of Micronano Liquid Metal Droplets140
5.2.6Fabrication of Micronano Liquid Metal Motors140
5.3Scientific and Technical Challenges141
5.4Fabrication of Magnetic Nano Liquid Metal142
5.5Nano Particles Enabled Magnetic Liquid Metal Materials142
5.6Liquid Metal Phagocytosis Effect to Make Functional Materials149
5.7Conclusion159
References160Chapter 6Liquid Metalbased Thermal Interface Material165
6.1About Thermal Interface Materials166
6.2Galliumbased Thermal Interface Materials167
6.2.1Preparation of GBTIM167
6.2.2Characterization of GBTIM167
6.3Practical Working of Galliumbased Thermal Interface Materials 169
6.4Liquid Metal Amalgams with Enhanced and Tunable Thermal
Properties175
6.5Performance Evaluation of Liquid Metal Amalgams177
6.5.1Material Preparation and Characterization177
6.5.2Chemical Composition Characterization180
6.5.3Characterization of Electrical and Thermal Conductivities183
6.5.4DSC Characterization185
6.5.5Mechanical Property Characterization186
6.5.6Adhesionguaranteed Direct Painting189
6.5.7Formabilityguaranteed Moulding190
6.6Thermally Conductive and Electrically Resistive TIM191
6.7Fabrication of Thermally Conductive and Electrically Resistive
TIM193
6.7.1Fabrication Principle193
6.7.2Characterization of LMP Grease194
6.7.3Performance of LMP Grease195
6.8Metallic Bond Enabled Wetting between Liquid Metal and Metal
Substrate203
6.8.1Metallic Bond Enabled Wetting Behavior at Liquid
GaCuGa2 Interfaces203
6.8.2Quantification205
6.8.3Theoretical Simulation206
6.9Bulk Expansion Effect of Galliumbased Thermal Interface
Material 215
6.9.1Experimental Phenomena215
6.9.2Influencing Factors216
6.9.3Material Characterization218
6.10Conclusion221
References222Chapter 7Low Melting Point Metal Enabled Phase Change Cooling227
7.1About Phase Change Materials228
7.2Classification of PCMs229
7.3Typical Features of Low Melting Point Metals as PCMs232
7.3.1Selection Criterion of PCMs232
7.3.2Properties of Low Melting Point Metal PCMs233
7.4Case of Using Low Melting Point Metal PCM for Smart Cooling of
USB Disk234
7.5Case of Using Low Melting Point Metal PCM for Smart Cooling
of Mobile Phone237
7.6Potential Application Areas of Low Melting Point Metal PCM246
7.6.1PCM Used in Solar Energy246
7.6.2PCM Used in Thermal Comfort Maintenance249
7.6.3PCM Used in Building Heat Storage252
7.6.4PCM Used in Thermal Management on Various
Electronic Devices 257
7.6.5PCM Used in Antilaser Heating262
7.7Theory to Quantify Phase Change Process of Low Melting Point
Metal 262
7.7.1Enthalpyporosity Method262
7.7.2Validation of Numerical Method264
7.7.3Comparison with Conventional PCM Paraffin265
7.7.4Dimensionless Correlations: Constant Wall Temperature269
7.7.5Dimensionless Correlations: Constant Heat Flux270
7.7.6Discussion on High Ra Number Condition271
7.8Phase Change of Low Melting Point Metal around Horizontal
Cylinder 272
7.8.1Theoretical Model273
7.8.2Comparison with Conventional PCM Paraffin276
7.8.3Constant Wall Temperature Case278
7.8.4Constant Wall Heat Flux Case281
7.9Low Melting Point Metal PCM Heat Sink with Internal Fins282
7.9.1Performance Enhancement of Low Melting Point Metal
PCM282
7.9.2PCM Preparation and Characterization282
7.9.3Experimental Setup284
7.9.4Transient Thermal Performance285
7.9.5Cyclic Performance287
7.9.6Numerical Modeling288
7.10Optimization of Low Melting Point Metal PCM Heat Sink290
7.10.1Optimization of PCM290
7.10.2Theoretical Evaluation291
7.10.3Problem Description293
7.10.4Numerical Method294
7.10.5Effect of Fin Number295
7.10.6Effect of Fin Width Fraction297
7.10.7Base Thickness and Structural Material298
7.10.8Heating Condition299
7.11Lattice Boltzmann Modeling of Phase Change of Low Melting
Point Metal 300
7.12Emerging Scientific Issues and Technical Challenges303
7.13Conclusion304
References305Chapter 8Fluidic Properties of Liquid Metal313
8.1Splashing Phenomena of Liquid Metal Droplet313
8.1.1About Impact of Liquid Metal Droplets314
8.1.2Experiments on Impact of Liquid Metal Droplets314
8.1.3Droplet Shapes during the Impact Dynamics316
8.1.4Quantification of the Impact Process319
8.1.5Splashing Shapes323
8.2Impact Dynamics of Water Film Coated Liquid Metal Droplet326
8.2.1Water Film Coated Liquid Metal Droplet326
8.2.2Impact Dynamics of Water Film Coated Liquid Metal
Droplet327
8.3Hybrid Fluids Made of Liquid Metal and Allied Solution334
8.4Fluidic Behaviors of Hybrid Liquid Metal and Solution335
8.4.1Electric Field Actuated Liquid Metal Flow335
8.4.2Selfdriven Motion of Liquid Metal337
8.4.3Coupled Fields on Liquid Metal Machine340
8.5Theoretical Foundation of Liquid Metal Flow341
8.5.1Physical and Chemical Properties of Gallium341
8.5.2Movement Theory342
8.5.3Deformation Theory345
8.6Theoretical Simulation Method346
8.6.1Volumeoffluid Method347
8.6.2Lattice Boltzmann Method348
8.6.3Boundary Integral Method349
8.6.4Finiteelement Method350
8.6.5Fronttracking Method350
8.7Challenges and Prospects351
8.8Conclusion352
References352Chapter 9Liquid Metal Flow Cooling and Its Applications in Diverse
Areas357
9.1Comparison between Liquid Metal Cooling and Water Cooling358
9.2Electromagnetic Pump Driven Liquid Metal Cooling363
9.3Design of Practical Liquid Metal Cooling Device377
9.3.1Thermal Resistance Evaluation Theory378
9.3.2Electromagnetic Pump Design Principles380
9.3.3Radiator Design Principles381
9.3.4System Fabrication and Characterization382
9.3.5System Cooling Capability Evaluation384
9.3.6Economic Analysis and Other Practical Issues385
9.4Rotational Magnetic Field Induced Flow Cooling of Liquid Metal388
9.5Liquid Metal Cooling for Thermal Management of High Power
LEDs390
9.5.1Liquid Metal Cooling of LED390
9.5.2Experimental Setup391
9.5.3Heat Dissipation Performance Evaluation392
9.5.4Liquid Metal Cooling of Large Power Street LED Lamp397
9.6Optimization of High Performance Liquid Metal CPU Cooling399
9.6.1Optimization Criterions399
9.6.2Schematic Thermal Resistance Model400
9.6.3Parameter Optimization of Electromagnetic Pump401
9.6.4Parameter Optimization of Fin Radiator404
9.6.5Product Design and Evaluation404
9.7Liquid Metal Cooling System for More Practical Systems408
9.7.1Liquid Metal Cooling for Desktop and Notebook
Computer408
9.7.2Cooling Transformer in Electricity Delivery via Liquid
Metal409
9.8Thermal Management of Liion Battery with Liquid Metal411
9.8.1About Cooling of Electric Vehicle411
9.8.2Theoretical Analysis412
9.8.3Cooling Capability Evaluation414
9.8.4Pump Power Consumption416
9.8.5Temperature Uniformity417
9.8.6Numerical Simulation Model418
9.8.7Computational Results420
9.9Thawing Issue of Frozen Liquid Metal Coolant424
9.10Conclusion427
References428Chapter 10Selfadaptable Liquid Metal Cooling432
10.1Electromagnetic Driving of Liquid Metal Coolant432
10.2Heat Driven Thermoelectricelectromagnetic Generator433
10.3Selfadaptive Waste Heat Driven Liquid Metal Cooling435
10.4Thermal Resistance Analysis on Heat Driven Liquid Metal
Cooling System440
10.5Thermosyphon Effect Driven Liquid Metal Cooling443
10.6Thermal Resistance Analysis on Thermosyphon Effect Driven
Liquid Metal Cooling 448
10.7Design of a Practical Selfdriven Liquid Metal Cooling Device
in a Closed Cabinet452
10.7.1Practical Application of Selfdriven Liquid Metal
Cooling452
10.7.2Cooling Capability Evaluation453
10.7.3Convective Heat Transfer Thermal Resistance of Liquid
Metal455
10.7.4System Fabrication and Test458
10.8Working of a Practical Selfdriven Liquid Metal Cooling Device
in a Closed Cabinet460
10.9Conclusion464
References465Chapter 11Liquid Metal Cooling in Small Space468
11.1Liquid Metalbased Miniaturized or Micro Chip Cooling Device469
11.1.1Miniaturized Chip Cooling Device469
11.1.2MEMSbased Chip Cooling Device470
11.1.3MEMSbased Liquid Metal Cooling Device in Harsh
Environment 472
11.2Heat Spreader Based on Room Temperature Liquid Metal472
11.2.1About Heat Spreader472
11.2.2Fundamental Equations473
11.2.3Performance Evaluation474
11.3Liquid Metal Blade Heat Dissipator478
11.4Liquid Metalbased Minimicro Channel Cooling Device485
11.4.1About Minimicro Channel Cooling Device485
11.4.2Pressure Difference under Different Coolant Volume
Flow487
11.4.3Convection Coefficient under Different Coolant Volume
Flow488
11.4.4Thermal Resistance under Different Pump Power489
11.4.5Flow Pattern Discrimination490
11.4.6Flow Resistance Comparison491
11.4.7Convective Heat Transfer Coefficient Comparison492
11.4.8Other Flowing Issues493
11.4.9Liquid Metal Alloybased Mini Channel Heat
Exchanger494
11.5Hybrid Minimicro Channel Heat Sink Based on Liquid Metal and
Water494
11.5.1Hybrid Minimicro Channel Heat Sink495
11.5.2Materials496
11.5.3Test Platform497
11.5.4Cooling Capability Comparison with Pure Water Cooling
System 498
11.6Flow and Thermal Modeling and Optimization of Micro
mini Channel Heat Sink502
11.6.1About Micromini Channel Heat Sink502
11.6.2Flow and Thermal Model503
11.6.3Optimization of Micromini Channel Heat Sink505
11.6.4Micro Channel Water Cooling505
11.6.5Channel Aspect Ratio506
11.6.6Channel Number and Width Ratio507
11.6.7Velocity508
11.6.8Base Thickness509
11.6.9Structural Material510
11.6.10Mini Channel Liquid Metal Cooling510
11.6.11Mini Channel Water Cooling513
11.7Conclusion514
References515Chapter 12Hybrid Cooling via Liquid Metal and Aqueous Solution517
12.1Electrically Driven Hybrid Cooling via Liquid Metal and
Aqueous Solution518
12.1.1Coolants and Driving Strategy518
12.1.2System Designing519
12.1.3Continuous Actuation of Liquid Metal Spheres Circular
Motion 519
12.1.4Heat Transfer Performance520
12.1.5Thermal Resistance Components521
12.1.6Heat Transfer Capacity under Different Driving Voltages522
12.1.7Electrical Driving of Liquid Metal Droplet523
12.1.8Liquid Metal Droplets Periodic Circular Motion in
Different Conditions 524
12.1.9More Potential Coolants with Improved Performances525
12.2Alternating Electric Field Actuated Liquid Metal Cooling526
12.2.1Liquid Metal as Water Driving Pump526
12.2.2Performance of the Liquid Metal Droplet Driven Flow527
12.3Selfdriving Thermopneumatic Liquid Metal Cooling or
Energy Harvesting535
12.3.1Hybrid Coolants towards Automatic Heating Driving535
12.3.2Running of Thermopneumatic Liquid Metal Energy
Harvester536
12.4Hybrid Liquid Metalwater Cooling System for Heat Dissipation541
12.4.1Combined Liquid Metal Heat Transport and Water
Cooling541
12.4.2Working Performances of Combined Liquid Metal and
Water Cooling542
12.4.3Theoretical Analysis on Combined Liquid Metal and
Water Cooling547
12.5Electromagnetic Driving Rotation of Hybrid Liquid Metal and
Solution Pool551
12.5.1Electromagnetic Driving Rotation of Hybrid Fluids551
12.5.2Rotational Motion of Liquid Metal in Electromagnetic
Field552
12.5.3Controlling the Rotating Motion of Liquid Metal Pool555
12.5.4Liquid Metal Patterns Induced by Electric Capillary
Force559
12.6Dynamic Interactions of Leidenfrost Droplets on Liquid Metal
Surface566
12.7Conclusion574
References575Chapter 13Liquid Metal for the Harvesting of Heat and Energy577
13.1Direct Harvesting of Solar Thermal Power or Lowgrade Heat580
13.2Liquid Metalbased Thermoelectric Generation581
13.3Thermionic Technology587
13.4Liquid Metalbased MHD Power Generation589
13.5Alkali Metalbased Thermoelectric Conversion Technology590
13.6Direct Solar Thermoelectric Power Generation591
13.7Liquid Metal Cooled Photovoltaic Cell596
13.7.1Thermal Management for Optical Concentration Solar
Cells596
13.7.2Experimental System597
13.7.3Performance Evaluation598
13.7.4Theoretical Evaluation on Thermal Resistance601
13.8Solar Thermionic Power Generation605
13.9MHD and AMTEC Technology609
13.10Cascade System612
13.11Remarks and Future Developments614
13.12Harvesting Heat to Generate Electricity via Liquid Metal
Thermosyphon Effect616
13.13Liquid Metal Thermal Joint619
13.14Conclusion626
References626Chapter 14Combinatorial Liquid Metal Heat Transfer towards Extreme
Cooling630
14.1Proposition of Combinatorial Liquid Metal Heat Transfer630
14.2Basic Cooling System633
14.2.1Abstract Division of A Cooling System633
14.2.2Heat Acquisition Segment635
14.2.3Heat Rejection Segment637
14.2.4Heat Transport Segment637
14.3LMPM PCM Combined Cooling System639
14.3.1LMPM PCM Cooling639
14.3.2LMPM PCM Against Thermal Shock642
14.4Liquid Metal Convectionbased Cooling Systems642
14.5All Liquid Metal Combined Cooling System645
14.6Other Alternative Combinations645
14.7Conclusion646
References647Appendix653
Index656
內容試閱:
The last two decades witness an explosive growth of personal computers,communication systems and workstations in the microelectronic industry. Meanwhile,the chip integration density is approaching its limit due tothermal barrierencountered. As is well known, overheating of a computer chip would result in shortened life, malfunction, low reliability and failure of work. Therefore, removal of the large amount of heat generated in the electronic components remains a big challenge facing modern system designers and thermal management engineers. However, most of the currently available advanced thermal management techniques are not sufficient enough to cope with the ever increasing devices power density like 100~1000 Wcm2 and the more compact package technology.
So far, tremendous efforts have been made to find out alternative methods for cooling the high power processors. Compared with the widely adopted air cooling,water cooling appears much efficient at drawing heat away from the processor and is therefore gradually becoming a major theme in developing new generation chip cooling device. With the forced convective flow of water, an improvement in heat transfer capacity over air cooling has been found to be more than a factor of 10. However,such method also implies its limitations. The small thermal conductivity of water may lower its effectiveness as a cooling fluid. Therefore,researchers are considering enhance the convective heat transfer effect of water by adding certain conductive nano particles such as copper or aluminum into the solution suspension. But improvement of the solutions heat conductivity through this way is still somewhat limited due to technical restrictions like particle oxygenation,susceptibility to fouling,particle deposition or conglomeration, degeneration of solution quality and flow jamming over the channels etc.
Realizing that a group of metals with an extremely low melting point such as gallium or its alloy have a far much larger thermal conductivity than that of the traditional coolant,at the year around 2000~2002,I came up to an idea to adopt such mediums as the cooling fluids for the thermal management of computer chip. A series of theoretical and experimental investigations have therefore been continuously carried out in my lab since then,aiming to develop the new generation liquid metal cooling category. As is now clear that,compared to the conventional heat transfer fluids,liquid metals with low melting point are rather desirable for thermal management of high power density devices owing to their large thermal conductivity and electrical conductivity,low vapor pressure,low dissolution in water and extensive temperature range over which they remain in the liquid phase. Particularly,liquid metal coolants can be pumped efficiently with compact magneto fluid dynamic(MFD)pumps,which are characterized by silent, vibration free,and low energy consumption rates because of the absence of moving components. Liquid metals can even realize high efficiency self driving through its thermosyphon effect and will offer better cooling capability than that of water under the same situations.
One thing worth of particularly pointing out is that,the normal boiling points of liquid metals are generally high,and hence the liquid metal cooling systems can be operated at near atmospheric pressures,and liquid metals can remain in liquid state at higher temperature compared to conventional fluids like water and various organic coolants which makes the design of a compact heat exchanger feasible. For example,the most classical liquid metal such as gallium has much higher evaporation point than that of water(2204.8℃ for gallium,and 100℃for water). Therefore,it can remain in a single liquid phase within a wide temperature range. This makes it possible to break up the restriction of the critical heat flux and thus effectively prevent devices from burning out. The key advantages of using liquid metals as the coolant lie in that they do not require operation at high pressure in order to obtain high temperatures and usually, the melting temperatures are low enough such that they can be used as coolants in thermal devices. As a result,their running usually involves pressure which is small compared to thermodynamic critical pressure of the fluid.
Among various kinds of liquid metals,mercury has been used in some earlier versions of fast breeder reactors. It was ever adopted as a thermal working fluid in macroscale systems for many years, before its dangers were well understood. Besides, sodium and potassium are also very good cooling fluids, and NaK (sodiumpotassium) alloy has been widely used in fast breeder reactors. Sodium is a normal coolant used in large power stations,and both lead and NaK have been used successfully for smaller generating rigs. However,they are quite reactive to air and water,and are therefore considered fire hazards.
Unlike the above two,gallium and its alloys including those composed from bismuth and its alloy have been proven to be perfect working fluids or medium for room temperature appliances especially computer chip,LED lamp etc. It owns a high specific heat capacity per unit volume,a low vapor pressure at room temperature,a less reactive nature when exposed to oxygen and water,and a high surface tension which impedes leakage. And these features warrant the future applications of gallium in the thermal management of high heat flux density area. Gallium forms alloys characterized by specific properties with the majority of metals and metalloids. Many of the gallium based alloys are low melting. The physical and mechanical properties of some metals can be enhanced when seeded with gallium. Gallium based alloys mainly consist of gallium, indium,and tin,or two of the three types. Overall,gallium and its alloys are endowed with low toxicity and low reactivity. Therefore,they are quickly adopted as a replacement for many applications that previously employed toxic liquid mercury or reactive NaK. Further,liquid metal with low melting point, as a new generation heat transfer medium,can be easily enhanced on its conductivity through loading with more conductive nano particles. With an extremely high conductivity however relatively small viscosity,such liquid metal could serve as an idealistic base solution or thermal interface medium which shows very promising future for the thermal management application in super CPU chip cooling or the situations requesting seriously high heat flux removal.
So far, systematic knowledge about the flow and heat transfer in room temperature liquid metal is rather limited which is however extremely important for future practices. To push forward further researches and possible applications along this important frontier,This book is dedicated to summarize the latest science and art of the liquid metal cooling as advanced over the past few years. The author would like to point out that, although the research related to the utilization of liquid metals as heat transfer media has begun since nearly half a century ago,technological interests derive mainly from the potential use of liquid metals as working fluids in the nuclear reactors. Within an extremely long period of time,researches basically are limited to those specific liquids like sodium,potassium or their alloy,and mercury,which have either high melting temperature or are just toxic and dangerous. Extensively applying the room temperature liquid metals especially gallium, bismuth and their alloy as the new coolant and heat transfer medium for the thermal management of computer chip have been unfortunately overlooked until the beginning of this century. With tremendous efforts and continuous researches ever made subsequently,it is now very clear that,the heat transfer enhancement by liquid metals,as a newly emerging technology in the electronic and various high heat flux fields, offers many brand new scientific and technical opportunities worth of pursuing in the coming time.
This book is an output of our labs more than 16 yearscontinuous academic endeavours. Over the past few years, a group of our faculties, post doctorial research fellows, graduate students and collaborators have made important contributions to mould this new area of liquid metal advanced cooling. The author would like to take this chance to express his sincere appreciations to those people who have offered their professional contribution: Dr. Ma Kunquan, Dr. Deng Yueguang, Dr. Gao Yunxia, Dr. Tang Jianbo, Dr. Wang Lei, Dr. Tan Sicong, Dr. Li Haiyan, Mr. Yang Xiaohu, Mr. Ge Haoshan, Mr. Mei Shengfu, Mr. Li Peipei, Mr. Xie Kaiwang, Mr. Li Teng, Prof. Deng Zhongshan and Prof. Zhou Yixin. Further, Dr. Sheng Lei offers very helpful assistance in gathering all the copyright permissions contained in this manuscript. Lastly but not least,I would like to also acknowledge the generous support from the Special Foundation of President of the Chinese Academy of Sciences,Frontier Project of the Chinese Academy of Sciences as well as the National Natural Science Foundation of China.
I hope that this book could serve as start for the academics and industries to quickly grasp the basics of the liquid metal cooling and thus better advance the related areas. I would also very much welcome any critical comments and constructive suggestions from the readers for me to further enhance this book which would be incorporated into its future possible updated version.
Liu Jing
October,2018