Answer:
the temperature of the aluminum at this time is 456.25° C
Explanation:
Given that:
width w of the aluminium slab = 0.05 m
the initial temperature = 25° C
h = 100 W/m²
The properties of Aluminium at temperature of 600° C by considering the conditions for which the storage unit is charged; we have ;
density ρ = 2702 kg/m³
thermal conductivity k = 231 W/m.K
Specific heat c = 1033 J/Kg.K
Let's first find the Biot Number Bi which can be expressed by the equation:
Bi = 0.0108
The time constant value is :
Considering Lumped capacitance analysis since value for Bi is less than 1
Then;
where;
which correlates with the change in the internal energy of the solid.
So;
The maximum value for the change in the internal energy of the solid is :
By equating the two previous equation together ; we have:
Similarly; we need to understand that the ratio of the energy storage to the maximum possible energy storage = 0.75
Thus;
So;
t = 1.386294361 × 697.79
t = 967.34 s
Finally; the temperature of Aluminium is determined as follows;
T - 600 = -575 × 0.25
T - 600 = -143.75
T = -143.75 + 600
T = 456.25° C
Hence; the temperature of the aluminum at this time is 456.25° C