THERMAL STORAGE

SENSIBLE-HEAT STORAGE TANK


Packed Bed Configuration
Large contact area between storage medium and working fluid

Volume: 2 m3
Optimal Ratio H/D = 2
3 Chambers

Storage medium: Magnetite (Fe3O4)
Advantages : natural product, availability, low cost, environmentally benign, non-flammable. High storage density.

Heat Transfer Fluid : Therminol SP Oil
TANK ASSEMBLY


Magnetite Placement: Mean Particle Size : 1 cm


Chamber Assembly


Overall Assembly – Measurement Instrumentation


Interconnection with Solar Field
LATENT HEAT STORAGE


Phase Change Materials (PCM)

• Store energy as latent heat of fusion
• This is recovered during subsequent material solidifcation
• Advantages of PCM: large storage capacity, thus smaller tank volume for the same amount of stored energy

Storage media under investigation (melting point):
D-Μannitol (165°C), Erythritol (120°C), Dimethyl terephthalate (142°C)

Storage Medium (PCM) In Encapsulated Form

• Specially designed spherical capsules with metal shell (steel)
• Thermocouples at different positions in the interior for temperature monitoring


Experimental investigation
• Thermal cycling trials inside an oven for testing the durability-tightness of capsules and stability of PCM thermophysical properties : melting/solidification point, latent heat of fusion, degree of subcooling, thermal capacity, thermal conductivity
• Use of reference material for estimating the capsule external heat transfer coefficient (T-history method)



Temperature variations during a thermal cycle
STORAGE TANK Packed-bed Configuration


Volume: 100 lit
• Cylindrical geometry, height/diameter ratio : H/D = 2
• 2 separate chambers : option for combining two different storage media
• Capsule diameter : 75 mm, number Ν ~ 200

Heat Transfer Fluid (HTF):
• Therminol SP Oil





Hydraulic loop for the implementation of various tank charging-discharging scenarios



Chamber assembly – Storage medium placement