When a material melts it absorbs its latent heat of fusion without rising in temperature; it gives the heat back as it solidifies. That makes latent storage compact and ideal when the user needs a steady temperature.
Paraffins and organic PCMs work from about 5 to 120 °C, salt hydrates in a similar range, and salts, eutectics and metallic PCMs at several hundred °C. Low thermal conductivity and encapsulation are the main design challenges.
Key facts
- Equation
- Q = m · (cp,s ΔT₁ + L + cp,l ΔT₂)
- Paraffin L
- ≈ 150–250 kJ/kg
- Strength
- Near-constant delivery temperature
- Maturity
- Commercial / emerging
Phase-change materials6
- Organic phase-change materials
- Paraffin-based materials
- Salt hydrates
- Eutectic mixtures
- Metallic and high-temperature PCMs
- Encapsulated PCM modules
Applications6
- Building temperature stabilisation
- Compact process-heat buffers
- Industrial waste heat recovery
- Cold-chain and cooling storage
- Electronics and battery thermal management
- High-temperature PCM for steam
Design issues6
- Low thermal conductivity — fins, graphite, heat pipes
- Supercooling and phase segregation
- Encapsulation and container compatibility
- Volume change on melting
- Long-term cycling stability
- Fire properties of organic PCM
Related calculators
Calculators are available to staff / admin only.
Related topics
- Phase Change MaterialsOrganic, salt-hydrate, eutectic and metallic PCMs — choosing the melting point, latent heat and encapsulation.
- Thermal BatteryIntegrated systems that turn electricity — often cheap renewable power — into stored high-temperature heat for steam, hot air or power.
- District CoolingChilled-water, ice and PCM storage shift cooling load to off-peak hours and shrink chiller plants.
- Sensible HeatThe simplest and most deployed principle: energy is stored by heating water, salts, oils or solids without a change of state.
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