Environmental Engineering Reference
In-Depth Information
TES
is a reserve of energy in the form of heat that can be deployed inde-
pendently of primary resources. It was developed to assist with several
applications of energy production and heating, including supplementing
the loading of utility scale solar thermal power plants. TES can be stored as
sensible heat, latent heat, or the potential heat of recombination in reversible
thermochemical reactions. This chapter addresses these modes of TES and
discusses design instructions and applications.
PhysicsofThermalEnergyStorage
TES requires the increase or decrease of the internal energy of a substance by
heating or cooling. Thermal energy is stored in materials that are classified
by one of three methods by which they store energy as heat:
Sensible heat
involves a temperature change of the storage material.
Latent heat
requires an isothermal phase change of the storage material (melt-
ing, freezing, vaporization, fusion, and crystallization).
Heat of reaction or thermochemical heat
is the result of a reversible ther-
mochemical reaction by the storage material.
Figure 7.3 illustrates the temperature change when thermal energy is added
to a nonreacting material. As heat is added to the material, its temperature
Hot Storage Material
Input
Cold Storage Material
Input
ermocline
(gradient)
FIGURE 7.3
Thermocline technology schematic. (From National Renewable Energy Laboratory. 2008.
TroughNet: Parabolic Trough Thermal Energy Storage Technology. http://www.nrel.gov/csp/
troughnet/thermal_energy_storage.html)
