The STL technology

Our expertise on phase change materials

CRISTOPIA has a unique expertise on Phase Change Materials (PCM), the results of more than 30 years of R&D in partnership with technical centres and universities in France and in Europe.

We have worked on all types of PCM (solid liquid transition) over a wide range temperatures of -64°C to +120°C: inorganic materials (hydrated salts) and organic materials (paraffins and fatty acids or bio PCM).

Our expertise focuses on PCM (formulation, nucleation, characterization, durability, recyclability,...) on the packaging and encapsulation of PCM, on encapsulation materials (compatibility between materials, ageing,...), on industrial manufacturing processes and the engineering of the storage system with PCM.

The storage volume and the thermal losses are reduced thanks to the STL.

Sizing request / catalogue


Latent heat thermal energy storage allows a very high energy density (6 to 12 times more important than sensitive storage energy). Storage volume and thermal losses are greatly reduced.

The STL is composed of a tank filled with nodules (balls) and heat transfer fluid. The nodules take up approximately 60% of the tank volume, the 40% remaining being occupied by the fluid. The number of nodules in a system determines both the heat exchange rate between the nodules and the heat transfer fluid and also the total energy stored in the STL.


The spherical nodules (balls) are blow moulded from a blend of polyolefins and filled with PCM (Phase Change Material). A range of PCMs allows thermal energy to be stored at temperatures between -33°C and +27°C.

The 98 mm diameter nodules (nodules AC and AN) are made for applications at low temperatures of -2.6 to -15°C and air conditioning systems at 0°C.

In addition to its outstanding thermal performance in terms of exchange capacity, CRISTOPIA's nodules have a long lifespan, the equivalent of 30 to 40 years of use under normal conditions. a custom made tank

The heat exchange between the nodules and the system is done by means of the heat transfer fluid within the tank.

The tank dimensions are calculated according to the installation and STL capacity.

The tank may be cylindrical (black steel), resisting pressures up to 10 bar, or rectangular (concrete or steel) for atmospheric service pressure. Cylindrical tanks can be horizeontal, vertical, installed indoors, outdoors or buried.

The STL allows efficient energy management with a high reliabilty. Substantial operating savings are gained each year.

Sizing request / catalogue

...with a MEG or MPG heat transfer fluid

The heat transfer fluid is made of water and mono ethylene glycol (MEG) or water and mono-propylene glycol (MPG). MEG or MPG concentration varies with the phase change temperature of the nodule.

What you need to know about the STL

To know more

Related articles

A solution which allows to manage important energy cooling needs for air-conditioning and industrial cooling.

Many benefits such as up to 70% reduction in installed chiller capacity, the use of electricity at the lowest prices, and management of the cooling production based on actual needs.

The STL is composed of a tank filled with nodules and heat transfer fluid (mixture of water and mono-ethylene glycol and water or mono-propylene glycol). MEG or MPG concentration varies with the phase change temperature of the nodule.