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Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
Thermal and airflow modeling methodology for Desktop PC
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Thermal and airflow modeling methodology for Desktop PC

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  • 1. Thermal and airflow modeling methodology for high power-desktop PC chassis 9 th July 2010 Jeehoon Choi
  • 2. Contents Introduction - Background & Motivation 1 Thermal and airflow design 2 Basic test – general desktop PC 3 Axial fan – design & analysis 4 High power desktop chassis – design & practice 5
  • 3. Introduction - Backgrounds & Motivation
  • 4. History on semiconductor development The growth of the electronic industries have been accelerated with the trend of the modularization, the miniaturization and the high integration. In the demands of ever increasing semiconductor performance for the extensive data and graphic processing, the powerful performance of the semiconductors has been developing nowadays. A Typical Microprocessor Actual size 1971 10 μ m Line Width (2,300 Transistors) ? 130-65nm Line Width (Single-Dual Core) 32nm Line width (Octa Core) 45nm Line Width (Quad Core) 22nm Line Width (This new product line will be established in 2011. ) 2001 2008
  • 5. The Needs for Electronic Cooling
    • Wire bond failure
    • Die fracture
    • Corrosion
    • Electrical overstress
    • Electromigration
    • Gate oxide breakdown
    • Ion diffusion causing parameter shifts
    • Output logic swing
    • Switching speed
    • Noise margins
    • Signal degradation
    Temperature 55% Sources of stress in electronics RELIABILITY MECHANICAL ELECTRICAL PERFORMANCE
  • 6. Cooling Technologies Passive Cooling Thermal insulation Standard conduction Natural convection Heat pipes Active Cooling Thermoelectric cooling (TEC) Forced air & Liquid convection Refrigerating & cryogenic cooling MEMS Cooling
  • 7. Cooling Technologies : Heat sink Users have been feeling inconvenient by a loud noise of the fan or not gratified with low temperature environment of CPUs because the cooling performance of its system depends mainly upon high flow rate of the fan . Folded fin heat sink Augmented fin heat sink Bonded fin heat sink Extruded fin heat sink Extruded Al heat sink with a fan Heat Sink
  • 8. Cooling Technologies : HP applications Heat pipe application ( 2 phases heat transfer) Thermaltake (Taiwan) Big Typhoon VX CPU Cooler Aerocool (Taiwan) Silverwind CPU Cooler Thermacore (USA) Heat sink embedded with HP Heat pipe Very high thermal conductivity Power flattening Efficient transport of concentrated heat Applications
  • 9. Cooling Technologies : Liquid cooling • Heat rejected outside the computer case • Flexible tubing • Significantly cheaper than refrigeration • Low pressure fluids • Unlimited air heat exchanger • More complex than air-cooling Reserve tank Coolant Radiator Fan Pump Liquid Cooling Jacket Heated Subject
  • 10. General Desktop PC - Airflow Rear Fan CPU, Heat Sink & Fan Power Supplier (PSU) Heat Sink (North Bridge & South Bridge) GPU Heat Sink & Fan DRAM Video Graphic card (GPU) Mother Board DVD Driver Hard Disk Driver (HDD) Thermally Advantaged Chassis(TAC) Design Guide(2008)
  • 11. Desktop PC components grouping Desktop PC Chassis Chipset CPU CPU Heat Sink CPU FAN Video Graphic Card (GPU) VGA Heat Sink VGA FAN Mother Board Grilles / Vents PSU (POWER SUPPLYER) Other PCI card HDD/DVD Drives Cooling parts Rear FAN Chipset SDRAM North Bridge Heat Sink / South Bridge Heat Sink PSU FAN Passive Cooling (Free convection) Active Cooling (Forced convection) core
  • 12. core CPU & GPU Coolers 가열된 공기 배출
    • 고발열 반도체 단일 냉각 기술에 의존한 냉각
    • - 다양한 냉각기에 의한 주요 소자 냉각
    • - 추가 발열 요소에 대한 대안 미흡
    • - 공기 온도 상승에 따른 소음도 향상
    • Chassis 내부의 공기 유동 개선의 어려움
    • - Chassis 중앙부분에서 와류 현상 발생
    • - 주변기기 장착시 Slot 하단과 밑면 사이
    • 와류 현상 발생 및 유동 정체 현상 미해결
    • - 공기 흡배기 효율 감소 및 작업 여건의
    • 악화 요소 상승
    Why is it necessary to obtain thermal and airflow modeling ? Chipset CPU Graphic Processing Unit (GPU) Chassis 내부 공기 온도 상승 Other PCI card CPU voltage regulator SDRAM PSU (POWER SUPPLYER) HDD/DVD Drives
  • 13. Tries to improve airflow Center of PSU Fresh air duct Desktop PC mounted with BTX M/B BTX mother board For ATX BTX mother board
  • 14. Ref. Internet Data Center report published on March, 2009 [Unit : Million] Year Even though more laptop PCs are in demand compared to desktop PCs, why is it necessary to optimize the thermal management for the desktop in future? For extensive data and graphic processing programs such as 3D games, CAD tools, simulation programs and so on, users have been preferring desktop PCs to laptop PCs so far. For those programs, the powerful performance of desktops are probably going to go on being required. Simultaneously, thermal problems are necessary to be solved, too. Is it necessary to cool down desktops ?
  • 15. Thermal Packaging Constraints For improving the cooling capacity of desktop chassis, 2nd, to enlarge the volume of chassis 3rd, to add heat exchangers such as heat pipes and etc. to the chassis 1st, to boost high airflow rate Increasing the volume of the chassis results in the increase of cost and is discrepant from the recent trends of compact PCs. Higher flow rate or additional local fans result in significant increase in noise, vibration problems and more power consumptions. 4 th , Mechanically robust, Low cost, reliable and efficient
  • 16. An improved chassis should be satisfied with aspects as mentioned under. 1. E ffectively cool ; the total heat dissipation of the desktop PC chassis : ~ 350W - CPU (130W) and GPU(70W) temperature junction should be lower than 80℃. 2. For less noise, vibration and power consumptions ; possible with design goals of below 35dBA 3. To meet the confined space of the desktop PC chassis ; for the recent trends of compact desktop PC (within 55 liter) 4. Simple structure for manufacturing friendly ; not to increase cost Design target for new improved chassis
  • 17. Thermal and airflow design
  • 18. Assumption 1 : Steady State, Steady Flow Process Assumption 2 : a) Negligible PE & KE change of airflow b) Negligible heat transfer from Chassis to Ambient c) Constant air properties Assumption 3 : Only “q” taken into consideration Thermal design principle Fan Power dissipation
  • 19. Thermal design principle
  • 20. System Impedance After the airflow has determined, the amount of resistance to it must be found. This resistance to flow is referred to as system impedance and is expressed in static pressure. : Static pressure : Load factor : air density : airflow rate : constant (n=1 laminar, n=2 turbulent flow)
  • 21. Fan Selection Parallel combination operation Series combination operation
  • 22. Basic test - general desktop PC
  • 23. Test desktop PC specification CPU Full loading Program (Prime 95) VGA Full loading Program (Fur mark) Item Manufacture Model/Specification Thermal dissipation (W) CPU INTEL Core Duo E8400 4GHz 70 GPU NVIDIA GeForce GS 250 / RAM 1024MB 50 Mother Board ASUS P5Q 20 Power Supply ZALMAN ZM1000-HP / 1000W 50 RAM SEC DDR SDRAM / 2GB 15 Hard Disk Drive Western Digital 600GB 10 Power : 217.15 Watt Voltage : 215 V Current : 1.01 A Full loads condition Full loads condition
  • 24. INLET OUTLET INLET OUTLET CASE 1 ; Down-blowing CPU cooler CASE 2 ; Tower type CPU cooler Test desktop’s airflow path Motherboard South Bridge VGA Power Supply DVD HDD RAM North Bridge CPU Motherboard South Bridge VGA Power Supply DVD HDD RAM North Bridge CPU
  • 25. CASE 1 Chassis’ each componet Temperature Low RPM mode – Chassis fans High RPM mode - Chassis fans Temperature contour picture taken by IR – CAMERA Test desktop’s thermal results (1) Item FAN Fan RPM range CPU 80 mm FAN INTEL Extrude box cooler 1700 (L)~ 3000(H) rpm GPU 80 mm FAN GPU cooler 1400(L) to 2700(H) rpm Chassis 120 mm FAN (Rear fan only) 1800(L) to 2000(H) rpm
  • 26. CASE 2 Chassis’ each componet Temperature Low RPM mode – Chassis fans High RPM mode - Chassis fans Temperature contour picture taken by IR – CAMERA Test desktop’s thermal results (2) Item FAN Reamarks CPU 110 mm FAN ZALMAN CPU cooler 1800(L) to 2800 (H) rpm GPU 80 mm FAN GPU cooler 1400(L) to 2700(H) rpm Chassis 120 mm FAN (Rear fan only) 1800 (L) to 2000 (H) rpm
  • 27. Test results
  • 28. Analysis (Performance curve)
  • 29. Axial fan - design & analysis
  • 30. FAN velocity contour FAN pressure contour FAN mesh generation Fan airflow simulation
    • Boundary Conditions
      • Static pressure : 0 Pa
      • Steady state
    • Governing Equations.
      • Navier-Stokes Equations
      • * Convective term : MUSCL (2 nd order)
      • * Pressure correction : SIMPLEC
      • * Turbulence model : MP k-EPS model
  • 31. Measuring airflow and static pressure Generally expressed in terms of the relationship between airflow and static pressure Required to generate such air flow anemometer Fine pressure gauge Vena contracta Fan controller Fan
  • 32. Measuring fan acoustic noise At a distance of 1m from the intake at a point above the center line of the intake 12V Fan speed controller Fan Microphone Sound level meter Anechoic Chamber Distance between microphone and sample = 1m
    • Background Noise : 17.3dB
    • RH : 36%
    • Temperature : 26.7℃
    Hygrometer : Relative humidity 25 % 25 ℃ Thermometer
  • 33. P-Q curve with acoustic noise
  • 34. Fan voltage vs. airflow rate
  • 35. High power desktop chassis - design & practice
  • 36. Thermal and airflow design (1)
  • 37. Additional fans only add 2 to 3 more dB to the total noise level. Thermal and airflow design (2)
  • 38. : “q” heat dissipation of each component (W) : “F” Fans’ work (W) : Airflow direction Thermal and airflow design (3) Motherboard South Bridge VGA Power Supply DVD HDD RAM North Bridge CPU Rear Fan Top Fan 1 Top Fan 2 Bottom Fan Internal Fan 1 Internal Fan 2 CPU FAN* VGA FAN Item Manufacture Model/Specification Thermal dissipation (W) CPU INTEL Intel Core i7-930 Bloomfield 2.8GHz 130 GPU NVIDIA GIGABYTE GTS UDV 512MB 70 Mother Board ASUS P6X58D-E STCOM 20 Power Supply ZALMAN ZM1000-HP / 1000W 80 RAM SEC DDR SDRAM / 2GB 30 Hard Disk Drive Western Digital 600GB 10 DVD Drive LGE 10
  • 39. Thermal and airflow design (4)
  • 40. Computational simulation
    • Boundary Conditions
      • Static pressure : 0 Pa
      • Steady state
    • Computational Grids
      • Tetra Mesh / about 30 millions
      • Prism layer
    • Governing Equations.
      • Navier-Stokes Equations
      • * Convective term : MUSCL (2 nd order)
      • * Pressure correction : SIMPLEC
      • * Turbulence model : MP k-EPS model
    Temperature contour Airflow Contour
  • 41. Thermal test apparatus Q- Q+ 100 Power supply unit Digital Power meter Data Acquisition IBM PC T-type Thermocouple 25 % Hygrometer : Relative Humidity Acrylic chamber CPU & VGA Burning S/W Desktop PC Ti Te Q+ Q- DT
  • 42. Results (1) CPU GPU Chipset (NB) RAM PSU Mean inside air Ambient air DT Simulation Results(℃) 47.2 77.2 51.9 43.5 43.2 33.1 25 7.9 Experimental Results(℃) 48.2 59.1 42.6 48.7 36.4 33.4 25.1 8.3 Real Error. (%) 2.07 23.4 17.9 11.1 15.7 6.6 - - Simulation Results Experimental Results Unit Airflow (Exhaust only) 81.32 82.38 CFM Air density 1.141 1.141 kg/m3 Specific heat 1005 1005 J/kgK Tm-Ta 7.9 8.3 K Heat dissipation 347.8 371.3 watt Sound Level 30.4 32.2 dBA Full Loading State Power : 367.65 Watt Voltage : 215 V Current : 1.71 A
  • 43. Physchometric calculation Results (2) Inside air Mean temperature 33.4 ℃ Relative humidity 30 % Dew point temperature 16.03 ℃ Web bulb temperature 22.29 ℃ Sat. vapor. Pressure 60.62 mbar Partial vapor Pressure 18.19 mbar Humidity ratio 0.0114 kg/kg Ethalphy (h1) 65.99 kJ/kg Specific volume 0.9 m3/kg Exhaust air Ambient temperature 29.1 ℃ Relative humidity 44 % Dew point temperature 20.02 ℃ Web bulb temperature 15.64 ℃ Sat. vapor Pressure 40.31 mbar Partial vapor Pressure 17.73 mbar Humidity ratio 0.01119 kg/kg Ethalphy (h2) 57.83 kJ/kg Specific volume 0.088 m3/kg H1-h2 8160 J/kg Heat dissipation 361.9946 Watt
  • 44. Results (3)
  • 45. Conclusion Thermal and airflow modeling methodology was performed to define desktop PC chassis and each semi-conductor cooling requirements for a chassis dissipating 350W, with an 130W CPU, 70W GPU and so on. With appropriate use of parallel exhaust fans along with intakes fans, the results Show that the desktop chassis having 350W heat dissipation can be satisfactorily cooled at the proper noise level (32dBA). Using intakes fans mounted inside the chassis, increasing heat dissipation of chipsets, RAMs and the other components on the motherboard is held sufficiently down. Besides the fans can be stimulated to raise both static pressure and airflow rate.
  • 46. Thank you very much !!!

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