Thermal Storage is required when the heat load is temporarily higher than the continuous capability of the thermal control system. Compact thermal storage systems use a Phase Change Material (PCM) with high latent heat. During high heat loads, the PCM changes from solid to liquid, absorbing the energy with its latent heat.

ACT’s Phase Change Material heat sink calculator provides initial scoping estimates for your thermal storage requirements, including approximate volume, weight, and temperature profile. The expected transient performance for three different PCM options suitable for your application is plotted. This calculator assumes a generally conservative fin design. ACT can design higher-performing custom solutions than what is predicted by the PCM calculator. Please contact us for more information.

Note that this calculator provides PCM options for values between -10°C to 85°C.

This scoping tool is intended to demonstrate that different PCMs offer a wide range of performance. The thermal physical property values used are representative of the paraffin and salt hydrate materials that are most commonly used. An optimized design will be dependent on each unique application. ACT provides design and analysis services to determine the PCM for your particular application. ACT does not manufacture or sell bulk Phase Change Material, but rather integrates it into custom heat exchanger or heat sink systems designed by ACT’s thermal engineers.

To discuss your results, please send your results to the thermal experts at ACT.

If you have difficulty with this calculator, please email us at with your input values or watch this use case example.