What Is Two-Phase Cooling?_
Two-phase cooling removes heat by letting a coolant boil — change from liquid to vapor — at the heat source, exploiting the large latent heat of vaporization to absorb heat at near-constant temperature. It appears in two forms relevant to GPUs: two-phase immersion, where servers sit in a low-boiling dielectric fluid, and two-phase direct-to-chip, where coolant boils inside cold plates. It contrasts with single-phase cooling, where the coolant stays liquid and only warms.
Technical Details
In single-phase liquid cooling, coolant absorbs heat by rising in temperature, so heat capacity is bounded by flow rate and allowable temperature rise. Two-phase cooling instead absorbs heat through the phase change from liquid to vapor, which carries far more heat per unit mass and holds the surface near the fluid's boiling point — beneficial for keeping high-power dies within tight temperature limits. Two-phase immersion uses engineered dielectric fluids that boil at low temperature; vapor rises to a condenser and returns as liquid. Two-phase direct-to-chip boils coolant inside the cold plate. The trade-offs are fluid cost and handling, condenser and containment design, and the maturity of supporting infrastructure. Current NVIDIA NVL72 systems use single-phase direct-to-chip cooling rather than two-phase, though two-phase is an active area of development for higher densities.
How Leviathan Systems Works with Two-Phase Cooling
The customer and OEM appoint qualified parties for the applicable cooling-system work and its acceptance. Leviathan does not install, connect, test, commission or maintain liquid systems. Any separately agreed physical IT installation or cabling work retains its own authorized scope and handoff.
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