PCM

Sensible Energy Storage with Water
Water is the most common form of energy storage in residential and commercial use. Under common temperatures, water stores heat by sensible energy storage, which means that for every certain amount of heat introduced to the water, the temperature rises. This temperature rise is consistent, so that if introducing a certain amount of heat raises the water temperature by 5°, introducing an additional identical amount of heat will raise it another 5° and so forth.

Latent thermal storage with PCMs
The term PCM is a commonly used abbreviation for ”phase change material", which means a material that changes its state from solid to liquid or liquid to gas. While changing its state, for example from solid to liquid the material absorbs a certain amount of heat, called "latent heat", happening at an almost constant temperature. When it is turned around, that is, from liquid to solid or from gaseous to liquid, the process will set free the energy already stored at a nearly constant level of temperature. Out of this range of changing its state, the described material behaves like a conventional, sensible storage device.

The TrendSetter Advantage
The TrendSetter approach for optimum performance is a hybrid of both sensible and latent heat storage. TrendSetter thermal tanks can be loaded with PCM installed, allowing for high sensible heat stored in the water while additional heat can be stored in the PCM to be released when required. Consider as an example a TrendSetter 200- gallon storage tank at 140°F. If the required tank temperature is 120oF, than the amount of useful heat stored in the tank is:

200 gallons x 8.33 lbs/gallon x (140°F – 120°F) = 33,320bTu.

With the addition of PCM, more heat can be stored in this tank than the sensible heat of the water alone. With a 200-gallon tank holding 195 gallons of water and 5 gallons of PCM, not only the sensible heat of the water is stored, but the sensible heat and latent heat of the PCM is stored as well.

Now here is the exciting part! If cold water is run through the TrendSetter tank heat exchanger to remove heat from the tank, the sensible heat of the tank falls. Let us say that we removed sufficient heat to drop the tank from 140°F to 100°F in a short period of time. At this time the cold water is shut off, and the PCM begins to release heat back into the tank