Physics / mechanism
Phase-change materials (PCMs) exploit latent heat absorption/release during solid–liquid transitions to buffer thermal loads isothermally. A material absorbs energy as it melts (latent heat, ΔH_f) without temperature rise, then releases it on solidification. Key parameters: latent heat density (kJ/kg or kJ/L), transition temperature (T_m), thermal conductivity (often poor: 0.1–0.5 W/m·K for organics, 5–35 W/m·K for metal alloys), cycle stability, and supercooling tendency. Common classes: paraffins (T_m 20–70 °C, ΔH ~200 kJ/kg), salt hydrates (ΔH ~250–300 kJ/kg, corrosive), sugar alcohols (erythritol: ΔH ~340 kJ/kg), and metallic alloys (gallium-based, bismuth alloys). State of the art: encapsulated PCM composites with graphene or metal-foam enhancement push effective conductivity to 5–15 W/m·K while retaining bulk latent capacity. Electronics cooling targets 45–85 °C window; building thermal mass targets 20–28 °C.
Competitive landscape
Competing thermal buffering approaches include sensible heat storage (simpler, lower density), heat pipes/vapor chambers (higher conductivity, no latent storage), thermoelectric coolers (active, power-hungry), and immersion/liquid cooling (datacenter-scale, infrastructure-heavy). Adjacent material classes: thermally conductive polymers, pyrolytic graphite sheets, and aerogel insulators address different parts of the thermal stack.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.