Comprehensive Analysis of Two-Phase Flow Boiling for IT Equipment Cooling: A System and Component-Level Approach

Abstract As part of CoolIT System Inc.’s ongoing assessment of liquid cooling technologies, the company performed an in-depth study of two-phase direct liquid cooling (2P DLC). The study focused on the technology’s commercial viability from a system design and operation perspective using a 2P DLC system set up in CoolIT’s Liquid Lab™ Innovation Centre coupled with extensive industry research. This paper outlines the study’s results, supplemented with research, and describes the inherent challenges system developers must address when developing a two-phase system. We examine how pressure drops affect system performance and evaluate the advantages and disadvantages of arranging components in a series configuration. The authors also examine the operational considerations of using refrigerants. In sum, the higher costs associated with the refrigerant and equipment required for high working pressures in a 2P DLC system, greater health and safety risks as well as legal liability risks, outweigh the perceived performance benefits for industry-wide deployments. This is especially true given the excellent thermal performance of simpler, more cost-effective single-phase direct liquid cooling (1P DLC). While the authors conclude that 2P DLC is not yet a viable solution for mass market production and adoption, further investigation is warranted to determine whether it is applicable for specific IT equipment applications.