Rock has often been suggested as a medium for the thermal storage of energy. A cylindrical piece of rock with diameter 10 m and height 20 m is used for the storage of thermal energy. The rock is insulated and has an average heat transfer coefficient, U = 0.28 kW/m2 K. The density of the rock material is 2,650 kg/m3 and its specific heat capacity is 0.72 kJ/kgK. The temperature of the rock is raised to 500C and the ambient temperature is 25C. Determine: a) The total energy stored in the rock in MWh. b) The temperature of the rock 12 h after the heating process
Rock has often been suggested as a medium for the thermal storage of energy.
A cylindrical piece of rock with diameter 10 m and height 20 m is used for the
storage of thermal energy. The rock is insulated and has an average heat
transfer coefficient, U = 0.28 kW/m2 K. The density of the rock material is
2,650 kg/m3 and its specific heat capacity is 0.72 kJ/kgK. The temperature of
the rock is raised to 500C and the ambient temperature is 25C. Determine:
a) The total energy stored in the rock in MWh.
b) The temperature of the rock 12 h after the heating process stops.
c) The heat that has escaped from the rock during this 12 h period.
d) The loss of exergy of the rock during this 12 h period.
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