shashwat phase change

Presentation onPhase Change Materials

(PCM)

By :-Shashwat MishraR.No - 201410102110068B.Tech – ME

What is a PCM ?

• A phase-change material (PCM) is a substance presenting a high heat of fusion, and capable of storing and releasing large amounts of energy.

• Heat energy is absorbed or released when the material changes from solid to liquid phase and vice versa, thus, being classified as latent heat storage (LHS) units.

PCM physical principle and behaviour

• Latent heat

Classification of PCM

Example :Water as a PCM

Heat (energy)

is transferred into the ice.

The heat is used to

break the bonds

between molecules,

not to increase the

average kinetic

energy of the

molecules.

Since the bonds among the ice molecules have been broken,

water is formed. The water

molecules, at this moment, have the

same average kinetic energy as

they did when they were ice.

Since the ice and water

molecules both have the same average kinetic

energy, they are at the

same Kelvin temperature

.

• Changing levels

Water as a PCM

PCM general applications

Application : Heating in building

Heating:• PCM mats are used on the roof and walls of the building.• It absorbs the heat during sunshine hours and melts.• The liquid PCM freezes during night and releases the heat

in the building.

• Costly• Coating reduces the air

permeability and moisture transmission etc.

• Only perform for short intervals • Does not absorb all the heat • Reduces the dimensional

stability

Limitations

Conclusions

• PCM provide solutions requiring much less volume than existing classic systems

• PCM materials present great advantages in buildings.

• It suitable for use in any region with climates with high demands in cooling and heating