Heat-driven cooling prototype could let data centers recycle waste heat for refrigeration

Researchers from Germany and Japan have built a prototype cooling device that uses shape-memory alloys to convert waste heat into mechanical motion, driving a refrigeration cycle without electricity. The system, detailed in Nature Energy, achieved a 12.9 K temperature span across the refrigerant film when heated to 86°C, and maintained a 2.2 K span when powered by an external 130°C heat source. This could enable data centers to recycle processor heat for cooling, reducing energy consumption.

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The prototype pairs two ultra-thin metal films: a 22-micrometer titanium-nickel actuator that contracts when heated, and a 26.5-micrometer titanium-nickel-iron refrigerant film that undergoes a reversible phase transition when stretched and released. This transition releases latent heat during loading and absorbs it during unloading, producing the cooling effect. The actuator converts thermal energy directly into the mechanical work needed to drive that cycle, eliminating the electric motor found in conventional systems.

The research positions this approach against existing cooling methods. Thermoelectric coolers, already common in compact electronics, reach only 10–15 percent of the theoretical reversed-Carnot efficiency limit — roughly a quarter of modern vapor-comp