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Liquid cooling has been used since the early mainframe days and to cool some supercomputers. More recently, air cooling became the predominant form of cooling for most computing systems. Over the past several years, however, many new liquid cooling technical developments and products have entered the market. This has been driven by several factors, such as the increased demand for greater power density, coupled with higher information technology (IT) performance for high performance computing (HPC) and some hyper-scale computing, and the overall industry focus on energy efficiency.
The Green Grid Association—a consortium that works to improve information and communications technology and data center resource efficiency worldwide—developed this white paper to provide a high-level overview of IT and facility considerations related to cooling, along with a guide to state-of-the-art liquid cooling technology. It is intended for chief technology officers and IT system architects, as well as data center designers, owners, and operators. The paper defines and clarifies liquid cooling terms, system boundaries, topologies, and heat transfer technologies. Through it, The Green Grid aims to give industry vendors and end users a cohesive picture of current products and related developments. The paper refers to existing terminology and methodologies from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Technical Committee 9.9 Liquid Cooling Guidelines (2016). It also includes recently developed liquid cooling technologies that may not be covered by current ASHRAE publications.
In this white paper, The Green Grid also examines and defines direct and indirect benefits for ITE systems, as well as factors for connection to existing facility infrastructure or the need for addition of supplemental heat rejection systems.
The white paper’s findings will serve as the foundation for a follow-up white paper from The Green Grid, IT Design Enabling Multi-Refresh Liquid Cooling, which will help establish recommendations for standardizing the interfaces of evolving liquid-cooled IT equipment to avoid or minimize facility-side changes.