# Heat Storage in Materials

## Energy stored as sensible heat in materials

Thermal energy can be stored as sensible heat in a material by raising its temperature.

The heat or energy storage can be calculated as

q = V ρ cp dt

= m cp dt                               (1)

where

q = sensible heat stored in the material (J, Btu)

V = volume of substance (m3, ft3)

ρ = density of substance (kg/m3, lb/ft3)

m = mass of substance (kg, lb)

cp = specific heat of the substance (J/kgoC, Btu/lboF)

dt = temperature change (oC, oF)

MaterialTemperature Range
(oC)
Density
ρ -
(kg/m3)
Specific Heat
- cp -
(J/kgoC)
Energy Density
(kJ/m3 oC)
Aluminum max. 660 (melting point) 2700 920 2484
Brick 1969 921 1813
Cast Iron max. 1150 (melting point) 7200 540 3889
Concrete 2305 920 2122
Fireclay   2200 1000 2200
50% Ethylene Glycol - 50% Water 0 - 100 1075 3480 3741
Dowtherm  A 12 - 260 867 2200 1907
Draw salt - 50% NaNO3 - 50% KNO3) (by weight) 220 - 540 1733 1550 2686
Granite   2400 790 1896
Liquid Sodium 100 - 760 750 1260 945
Molten Salt - 50% KNO3 - 40% NaNO2 - 7% NaNO3 (by weight) 142 - 540 1680 1560 2620
Oak 769 2385 1833
Pine 496 2803 1391
Taconite   3200 800 2560
Therminol 66 -9 - 343 750 2100 1575
Water 0 - 100 1000 4190 4190
• 1 kJ/(kg K) = 0.2389 Btu/(lbm oF)

### Example - Heat stored in Granite

Heat is stored in 2 m3 granite by heating it from 20 oC to 40 oC. The heat stored can be calculated as

q = (2 m3) (2400 kg/m3) (790 J/kgoC) ((40 oC) - (20 oC))

= 75840 kJ

qkWh  = (75840 kJ) / (3600 s/h)

= 21 kWh

### Example - Heat required to to heat Water

The heat required to to heat 1 pound of water by 1 degree Fahrenheit when specific heat of water is 1.0 Btu/lboF can be calculated as

q = (1 lb) (1.0 Btu/lboF) (1 oF)

= 1 Btu

## Tag Search

• en: sensible heat energy energy storage materials
• es: materiales de almacenamiento de energía de energía de calor sensato
• de: Eigenwärme Energie Energiespeichermaterialien

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