Difference between steady state and unsteady state heat transfer [with Pdf]

The main difference between steady state and unsteady state heat transfer is that in steady-state the temperature at a point in the object does not change with respect to time while in the case of the unsteady state heat transfer the temperature at a specific point in the object increases or decreases with respect to time.

What is steady state heat transfer?

The heat transfer process that does not get affected by the time interval is known as steady-state heat transfer. In this type of heat transfer, the temperature of the object does not change with respect to time.

What is unsteady state heat transfer?

The heat transfer process that gets affected by the time interval is known as the unsteady state heat transfer. In this type of heat transfer, the temperature of the object increases or decreases with respect to time.

Difference between steady state and unsteady state heat transfer

Sr. No.Steady state heat transferUnsteady state heat transfer
1]The steady state heat transfer is denoted by, (∂t/∂τ = 0).The unsteady state heat transfer is denoted by, (∂t/∂τ ≠ 0).
2]The temperature of the object doesn’t vary with respect to time.The temperature of the object changes with respect to time.
3]No heat diffusion occurs in the object.Heat diffusion occurs in the object.
4]For the steady-state heat transfer, the energy entering the object is equal to the energy leaving from the object, Ein = Eout.For the unsteady state heat transfer, the energy entering the object is not equal to the energy leaving from the object, Ein ≠ Eout.
5]The change in the internal energy of the object is zero.The change in the internal energy of the object is not equal to zero.
6]Example: Heat generation because of electrical currentExample: Heating or cooling of water, Heating of metal in a furnace

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