This invention introduces a regenerative preheater for phase change cooling that reuses waste heat to preheat refrigerant, reducing subcooling, improving efficiency, and eliminating the need for external heaters.
Background: Data centers and high-performance computing systems, especially those powering AI, generate extreme heat that challenges cooling systems. Two-phase liquid cooling is effective, but its efficiency drops when subcooled refrigerant enters evaporators, creating uneven cooling and thermal throttling. Current fixes, such as electrical heaters, add cost, power draw, and system complexity. A passive, efficient solution is needed to stabilize performance while cutting energy use.
Technology Overview: This invention introduces a regenerative preheater system that transfers heat from warmed refrigerant exiting evaporators to subcooled refrigerant entering them. This passive preheating raises the refrigerant closer to its boiling point, boosting latent heat transfer and stabilizing evaporator performance. Key components include a manifold for distributing preheated refrigerant, optional localized heat exchangers for rack-level optimization, and passive regulation to ensure uniform cooling. The design eliminates the need for power-hungry electrical heaters, reduces system complexity, and ensures consistent operation.
Advantages: • Improves evaporator efficiency by reducing refrigerant subcooling • Prevents thermal throttling in CPUs, GPUs, and AI hardware • Provides uniform cooling across vertically stacked servers • Reduces flow instabilities and backpressure in two-phase cooling loops • Eliminates external electrical heaters, saving energy • Simplifies cooling system design with passive regulation
Applications: • High-density data center cooling for AI and HPC servers • Thermal management in electric vehicles and autonomous systems • Aerospace and defense cooling for lasers, radar, and avionics • Cooling for telecommunications and 5G infrastructure • Heat management in medical imaging and scientific instruments
Intellectual Property Summary: • US Utility Application 18/376,435 – Filed 10/03/2023, Allowed 07/15/2025, Status: Allowed • US Utility Application 12/363,865 – Filed 07/15/2025, Status: Pending
Stage of Development: Laboratory validated with rack-level experimental demonstration showing improved cooling efficiency and stability in high-power systems. TRL ~5–6.
Licensing Status: This technology is available for licensing.
Licensing Potential: Strong potential for adoption in data center cooling, electric vehicle thermal systems, aerospace, telecommunications, and medical device markets where high-efficiency thermal management is critical.
Additional Information: Experimental performance data, system integration details, and energy savings analyses available upon request.
Inventors: Sadegh Khalili, Bahgat Sammakia