Requirement for PCMs:

• phase change temperature range should fit to the system

• should have high heat density

• should be stable (for at least for 25 years)

• shouldn’t be toxic, corrosive, explosive or flammable

• most important: it shouldn’t give more tasks to the operation staff

There are different types of PCMs:

• paraffins: stable materials with usually between 40÷80 °C melting temperature, with medium density and heat capacity.

• salt hydrates: has high density and heat capacity, usually not stable, can be corrosive, toxic. It is crucial to use additives and choose the right material.

• bio PCMs: plant or animal-based materials, usually stable materials, with similar density and heat capacity to paraffins, always safe to use then, many of them has food-grade certificates.