Immersion Cooling Systems

Immersion cooling is a thermal management technique that submerges electronic components in dielectric liquids to dissipate heat directly at the source. Utilizing fluids with high thermal conductivity and electrical insulation properties, this method eliminates the need for fans and reduces reliance on energy-intensive air conditioning. It supports high-density computing applications like artificial intelligence (AI), high-performance computing (HPC), and cryptocurrency mining, with cooling capacities reaching 100 kW per tank. The technology operates at higher temperatures than air cooling, enabling efficient waste heat recovery and reducing power consumption. Global market revenue for liquid cooling reached $745 million in 2023, with projected growth driven by escalating computational demands.

Dielectric fluids absorb heat 20× more efficiently than air due to superior thermal conductivity and volumetric heat capacity. Single-phase systems circulate liquid coolants (e.g., synthetic hydrocarbons) through heat exchangers without phase change, while two-phase systems leverage latent heat absorption during fluid vaporization. The latter achieves 98% heat removal from components but faces challenges related to fluid toxicity and complexity.

• Single-Phase Immersion: Uses open baths with non-evaporative fluids like mineral oils or biodegradable synthetics (e.g., Shell S5X). Coolant circulates via pumps to external heat exchangers, supporting temperatures up to 65°C. Power Usage Effectiveness (PUE) ranges from 1.05 to 1.10.
• Two-Phase Immersion: Employs low-boiling-point fluorochemicals that vaporize upon contact with hot components. Vapor condenses on cooled coils and returns to liquid form. Though highly efficient (PUE: 1.02–1.04), fluorocarbon-based fluids raise environmental and health concerns due to perfluoroalkyl substances (PFAS).
• Hybrid Designs: Integrate cold plates within immersion tanks for targeted cooling of high-heat components like GPUs.

• Synthetic Hydrocarbons: Engineered for stability and low toxicity (e.g., Submer’s SmartCoolant). Exhibit flash points above 160°C, rated 0-1-0 by the NFPA for minimal flammability risk.
• Fluorochemicals: Used in two-phase systems for low boiling points but contain persistent "forever chemicals" linked to cancer.
• Bio-Based Alternatives: Derived from biological waste, reducing reliance on petroleum. Asperitas’ fluids operate at 40°C, enabling dry cooling in diverse climates

• Sulfur compounds in mineral oils corrode copper and zinc in electronics.
• Polyvinyl chloride (PVC) cable jackets leach plasticizers into fluids, requiring synthetic rubber-clad alternatives.
• Thermal pastes require replacement with indium foil or conductive epoxies to prevent degradation in liquids.

Per- and polyfluoroalkyl substances (PFAS) in two-phase fluids have led to lawsuits and production halts. Microsoft and Meta suspended research due to carcinogenic risks. Single-phase bio-fluids mitigate this via OECD 301-certified biodegradability.

• Space Limitations: Immersion tanks require ceiling-mounted cranes for hardware servicing, demanding 3–4 feet of overhead clearance. Many facilities lack structural support for crane loads.
• Power Infrastructure: Coolant distribution units (CDUs) need direct UPS-backed power feeds, necessitating electrical reconfiguration.
• Warranty Voidance: Hardware manufacturers often invalidate warranties for liquid-submerged components.

• Fluid Maintenance: Regular sampling and filtering prevent bacterial growth and particulate accumulation.
• Leak Management: Sealed tanks with redundant containment vessels minimize spill risks. Fluid disposal costs escalate if classified as hazardous.

Immersion cooling reduces energy use by 30–50% compared to air cooling. It achieves PUEs below 1.10 by eliminating chiller plants and leveraging waste heat for district heating. Water consumption drops near zero, as dry coolers replace evaporative towers.

Captured heat (up to 40°C output) supports agricultural greenhouses, swimming pools, and industrial processes. Bitcoin mining operations increasingly repurpose heat for residential heating, offsetting operational costs.

• AI/GPU Clusters: NVIDIA’s DGX BasePOD racks (35 kW) use immersion for sustained 1,200W GPU performance.
• Cryptocurrency Mining: Continuous operation rigs achieve stability with 75°C fluid temperatures .
• Edge Computing: Modular tanks enable deployment in non-traditional spaces like office basements or rural sites.

• Hyperscalers: NTT’s Mumbai facility reduced cooling energy by 30% using hybrid immersion systems.
• Barriers: Two-phase systems remain niche due to fluid toxicity; single-phase dominates 85% of commercial deployments.