Liquid Coolant Bazaar: Everything you always wanted to know about Immersion but were afraid to ask.

Author: Rolf Brink, CEO, Promersion; Rich Lappenbusch, Senior Principal, Super Micro Computer Inc.; Allison Boen, Consultant, Alcatex Data Center Services Collection: 2023 Global Summit - Cooling Environments

Summary

This session was a live Q&A forum at OCP Global Summit 2023, structured around a physical "bazaar" displaying 18 immersion cooling fluids from 13 manufacturers — all submitted as professional samples that passed cursory business-level due diligence. No NDA samples were accepted. All 13 coolant manufacturers whose products were exhibited were invited to attend without incentive or discount. Moderators included Rolf Brink (Promersion), Rich Lappenbusch (Super Micro), and Allison Boen (Alcatex), joined by the full roster of OCP Immersion Project workstream leads. The immersion project is identified as the largest project within OCP, not because immersion is an easy or dominant market, but because of the enormous amount of open engineering work the industry must complete for the technology to mature.

Discussion ranged across biodegradability standards (60% biodegradability in 28 days under ASTM standard being the relevant threshold), fluid end-of-life and regeneration (hydrocarbon-based fluids can be repurified approximately 40-50 times before significant top-up is needed), accelerated aging methodology for both fluids and components (proposal in review: two-week accelerated aging at 80°C for material side), signal integrity in immersion (dielectric constants of ~2.0 for immersion fluids require impedance retuning of connectors; Kai from Intel reported no long-term signal degradation observed in large-scale hyperscale deployments), and optical connections (currently incompatible with direct immersion due to fluid layer between transceiver and connector and chemical attack on cable materials). Rolf Brink articulated a key framing: current immersion implementations are at the starting point of an innovation curve — they move fluid in a basic open-bath configuration, with none of the "precision cooling" intelligence that could dramatically raise power density ceilings. An Intel/Sauro demonstration at the summit showed that mechanically directing flow through a heatsink enables chips to operate at 800-900 W without issue.

A 10-year accelerated aging study by APL Landow (Germany) was announced as forthcoming and the OCP community was invited to collaborate on the results. Super Micro representatives reported 11 years of real-world immersion tank testing, with unexpectedly high durability — tanks deployed 11 years ago continue to operate. CGG, an oil-and-gas company that plots the ocean floor using supercomputers, was cited as having a multi-generation, multi-fluid immersion deployment running over 10 years with monthly fluid sampling sent to independent labs. The principle stated: if a system runs cleanly for two months, it will typically run for 10 years with lower maintenance than any other cooling approach.