Enough Hot Air: The Role of Immersion Cooling

TL;DR

This paper compares air cooling and immersion cooling for data centers, showing immersion cooling significantly reduces energy use and space but involves higher maintenance and reliability challenges.

Contribution

It provides a quantitative comparison of air and immersion cooling, highlighting the benefits and trade-offs, and discusses practical considerations for implementation.

Findings

Immersion cooling reduces energy consumption by about 50%.

It decreases occupied space by approximately two-thirds.

Immersion cooling allows higher rack power densities.

Abstract

Air cooling is the traditional solution to chill servers in data centers. However, the continuous increase in global data center energy consumption combined with the increase of the racks' power dissipation calls for the use of more efficient alternatives. Immersion cooling is one such alternative. In this paper, we quantitatively examine and compare air cooling and immersion cooling solutions. The examined characteristics include power usage efficiency (PUE), computing and power density, cost, and maintenance overheads. A direct comparison shows a reduction of about 50% in energy consumption and a reduction of about two-thirds of the occupied space, by using immersion cooling. In addition, the higher heat capacity of used liquids in immersion cooling compared to air allows for much higher rack power densities. Moreover, immersion cooling requires less capital and operational expenditures. However, challenging maintenance procedures together with the increased number of IT failures are the main downsides. By selecting immersion cooling, cloud providers must trade-off the decrease in energy and cost and the increase in power density with its higher maintenance and reliability concerns. Finally, we argue that retrofitting an air-cooled data center with immersion cooling will result in high costs and is generally not recommended.