Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
CPU Thermal Management: Intel IHS with Air-Cooling (Old Technology to Be Replaced or Already Being Replaced)
Existing Technology
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
CPU Thermal Management: Geometry for Air-Cooled System
Courtesy of IBM
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
CPU Thermal Assembly: Air-Cooling
Courtesy of IBM
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
IBM Thermal Conductive Module for Mainframes (Existing Technology to Be Replaced)
Courtesy of IBM
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Possible Refrigerated Cooling System for Multiple CPU’s
Courtesy of IBM
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
CPU Microchannel Flow Boiling Cooling: Multiple CPU’s
Cross-section of computer chips with evaporator, Schmidt and Notohardjono [55].
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
CPU Microchannel Single-Phase Cooling: Colgan et al.
Figure 1 3-D rendering of assembled microchannel cooler of Colgan et al. [5].
A very low heat sink thermal resistance was obtained by Colgan et al. [5] in a single-phase silicon microchannel cooler. They used several different staggered fin configurations. The channels were 180 µm deep, either 65 µm or 75 µm wide, and the fin length was either 210 µm or 250 µm. The geometry of their assembled cooler is shown in Figure 1. Furthermore, they cooled a thermal test chip power density greater than 300 W/cm2 with a microchannel heat sink bonded to it and thus packaged in a single chip module.
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Dual cold plate pumped liquid cooling system – Gernert et al (2006)
Pump
Heat Spreaders for CPU
Air-cooled compact HE
Note: System would be similar for a two-phase (boiling) heat spreader.
CPU Microchannel Single-Phase Cooling: Gernert et al.
Gernert et al [9] developed a single phase, pumped liquid cooling system (LCS) for desktop computers. The LCS has the ability to handle heat fluxes up to 250 W/cm2 and can operate below 0 oC because it uses a mixture of water and propylene glycol as the coolant.
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
CPU Microchannel Flow Boiling Cooling: LTCM Studies
Multi-microchannels test section used at LTCM to dissipate 350 W/cm2 with refrigerant.
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Heat Conduction Simulations: Considerations for Implementation
C hip with 300 W/c m2 power density Therma l Inte rfa c e
Hea t Exc hanger
• Specification of geometry to be simulated. • Choice of boundary conditions for non-heated external surfaces (adiabatic b.c.’s?) • Choice of internal channel b.c.’s for heat transfer coefficients (htc is function of q). • 2-d vs. 3-d: 1st is less expensive and faster while 3-d effects should be looked at in final or near final designs. • Simulate just the copper (or silicon) heat spreader, the spreader plus thermal paste or the spreader, paste and silicon chip with its actual heat flux distribution (best). • Input/interface local flow boiling heat transfer calculations and two-phase pressure drops into software package. • Input/interface critical heat flux (critical vapor quality) calculation into software package and also diabatic flow pattern map. • Transient effects of 3-zone model on wall temperatures, hot spots and fluctuations in heat flux should be addressed.
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Example of Cooling Element Design Specifications
Power density W/cm2 300 Chip surface mm2 20×20 Chip material - Silicon Chip thickness mm 0.8 Max. chip temp. °C 85
Coolant inlet temp. °C 20
Absolute pressure bar < 5
Max. pump volume flowrate @ 1bar
l/min 4
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Evaporator geometry #4
20 rectangular channels 0.5 x 3mm
Laboratoire de Transfert de Chaleur et de Masse
ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
3D temperature distribution 20 rectangular channels 2 x 2 x 30mm
3D simulation R-245fa, Tsat=20oC, L=20mm
Evaporator material: copper Max 65.375
Min 47.145