Materials Design for Data Center Thermal Management and Waste Heat Recovery: Dielectric Fluids, Gallium Liquid Metals, and Embedded Two-Phase Cooling

Artificial intelligence (AI) and large language model (LLM) data centers are projected to consume more than 1,000 TWh of electricity annually by 2026, with nearly all of this energy ultimately rejected as heat. This work reframes data center thermal management as a materials design problem in which coolant selection governs the thermal pathway, determines the achievable coolant outlet temperature, and consequently defines the quality and recoverability of waste heat. Three generations of cooling technologies are evaluated.

Dielectric immersion fluids deliver outlet temperatures of 65-75 °C, enabling direct integration with district heating networks without heat pumps while eliminating cooling water consumption. Gallium-based liquid metal coolants provide thermal conductivities 200-600 times higher than dielectric fluids and reduce transient temperature rise by 60-68%, enabling higher operating temperatures and improved heat recovery. Embedded two-phase microfluidic cooling further advances thermal performance by transferring phase change directly to the chip surface, sustaining heat fluxes approaching 1 kW cm⁻² while maximizing recoverable thermal energy.

Across these cooling generations, coolant composition-and therefore the melting range-should be regarded as a design variable rather than a fixed material property, allowing liquid metal coolants to be engineered for different operating conditions. The results demonstrate that coolant materials selection is not solely a thermal management decision but also an energy systems design choice that directly influences waste heat utilization, water consumption, and carbon emissions.