Nomenclature Q Heat load (W) COP Coefficient of Performance I Electrical current (Amps) T Temperature (°C) R Electrical resistance (Ohms) Z TE Figure of Merit (1/K) where Z = α2 / (ρ λ) Greek Letters Δ Change in value θ Thermal resistance (°C/W) ρ Electrical resistivity (Ohm-cm) α Seebeck coefficient (V/K) λ Thermal conductivity … [Read more...]
Liquid Cooling is Back
Introduction IBM announced its return to water cooling on April 19, 2005 with the introduction of a water cooled heat exchanger mounted to the back cover of a 19 inch rack. This is the first of the major datacom equipment manufacturers to employ water cooling for a rack of CMOS processors, using a cooling distribution unit supplying the water and rejecting the heat load to … [Read more...]
Review of Low Profile Cold Plate Technology for High Density Servers
Introduction Water cooling of computers was introduced more than twenty years ago, but had disappeared from the mainstream by the mid 1990s. The conversion of chip technology from bipolar to CMOS (complementary metal oxide semiconductor) was the main reason. As chip powers continue to increase, water cooling appears likely to become mainstream again. In the current market, the … [Read more...]
Threatened With a Pipe
I have become a Heel Dragger. When natural convection was all the rage, I was touting fans. Once fan cooling became the status quo, I started dropping hints about heat pipes and thermoelectric coolers. The technology roadmap showed nothing but higher power ahead, and I would soon need those fancier cooling tools. Now everybody senses that this air cooling act is growing stale, … [Read more...]
Server Design Challenges for the High-heat-load Internet Data Center
Introduction Microprocessor and system thermal management are linked to facility cooling: power dissipation and cooling techniques employed at one end of the size scale have cascading impacts at the other extreme (Figure 1). For example, ineffective airflow distribution or insufficient underfloor static pressure in a data center can reduce the supply airflow rate from … [Read more...]
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