Question

Thermal Storage Solar heating of a house is much more efficient if there is a way to store the thermal energy collected during the day to warm the house at night. Suppose one solar-heated home utilizes a concrete slab of area 13 m2 and 26 cm thick. Model the concrete slab as having a surface area of 24 m2 and surrounded by an environment 5.0 ?C cooler than the concrete. If its emissivity is 0.94, what is the rate at which the concrete loses thermal energy by radiation at sunset?

Answer 1

Rate at which thermal energy is lost by radiation is

where Emissivity , Surface area ,

is the temperature of surroundings and is the temperature of concrete at the time of sunset.

If the Temperature of concrete at the time of sunset is (say)

Then