Solid-state cooler uses waste heat for refrigeration, potentially for data centers

Heat-Driven Cooling System Developed

Researchers from the Karlsruhe Institute of Technology (KIT) and the University of Tsukuba have demonstrated a novel solid-state cooling system. This system utilizes heat to generate the mechanical work necessary for refrigeration, a departure from traditional methods that rely on electrically powered actuators. The findings were published in Nature Energy on August 28.

How the Prototype Works

The prototype integrates two ultra-thin metal films: a 22-micrometer titanium-nickel (TiNi) shape-memory film acts as an actuator, contracting when heated to convert thermal energy into mechanical motion. This motion then stretches and releases a 26.5-micrometer titanium-nickel-iron (TiNiFe) refrigerant film, which undergoes a phase transition to produce cooling. In lab tests, heating the actuator to 86°C created a 12.9 K temperature span across the refrigerant film and a 4.0 K span across the device. When driven by an external 130°C heat source, the device maintained a 2.2 K temperature span.

Implications for Waste Heat Recycling

This technology presents a potential pathway for processors and data centers to repurpose their own waste heat for cooling purposes. By using an external heat source to drive the cooling mechanism, the system could reduce reliance on electrical power for refrigeration. This approach offers an alternative to conventional vapor-compression cooling systems, which require electrically driven compressors and often use refrigerants with high global warming potential.

Comparison to Existing Cooling Technologies

Traditional refrigeration systems primarily use vapor-compression cooling, which is efficient but requires electricity and specific refrigerants. Solid-state cooling, like thermoelectric devices, moves heat without a compressor-and-refrigerant loop. However, thermoelectric coolers typically achieve only 10% to 15% of the theoretical reversed-Carnot efficiency limit, which is about one-quarter of modern vapor-compression systems. The new elastocaloric system offers a different solid-state approach by directly converting thermal energy into mechanical work for cooling.