Green performance characterization of electronics cooling methods: From air through hybrid to direct two phase touch cooling

As high-powered computing (HPC) and telecom server equipment continues to move towards higher power densities, reaching over 3 kW per blade [1], cooling at the blade, cabinet, and data center level becomes an increasingly important concern for data centers as well as for computing equipment manufacturers. In many data centers, cooling systems account for up to ~70% of the total electricity consumed [2], resulting in an unnecessarily high operating expense. As many equipment manufacturers move to higher powers, air cooling at the blade-level becomes more of a challenge, and liquid cooling options are often implemented to allow equipment to operate at higher powers. Pumped liquid cooling has been shown to be more efficient than air cooling in terms of thermal resistance and cost of electricity [3], and operating expense [4], but not all liquid-cooled methods have the same advantages. This article examines three different liquid cooling approaches, shown on Figure 1, to provide a comparison of the advantages and disadvantages of each option.