The value of Biot number is very small (less then 0.1)
Since Biot number is the ratio of conduction resistance to convection resistance and in lumped heat analysis convection resistance ≫ conduction resistance, it means that conduction resistance of solid is negligible as compared to convection resistance of fluid.
The time constant of a thermocouple is the time taken to attain
Time constant of the thermocouple represents the time required for the thermocouple to record 63.2% of initial temperature difference.
In a lumped parameter model, the temperature variation with time is
Hence temperature variation will be exponential.
One dimensional unsteady state heat transfer equation for a sphere with heat generation at the rate q can be written
Transient three-dimensional heat conduction is governed by ONE of the following differential equations (α - thermal diffusivity, k - thermal conductivity and ψ - volumetric rate of heat generation)
Steady two-dimensional heat conduction takes place in the body shown in the figure below. The normal temperature gradients over surface Pand Q can be considered to be uniform. The temperature gradient at surface Q is equal to 10 K/m. Surface Pand Q are maintained at constant temperatures as shown in the figure, while the remaining part of the boundary is insulated. The body has a constant thermal conductivity of 0.1 W/mK. The value and at surface P are
A large concrete slab 1 m thick has one dimensional temperature distribution:
T = 4 - 10x + 20x2 + 10x3
where T is temperature and x is distance from one face towards other face of wail. If the slab material has thermal diffusivity of 2 x 10-3m2/hr, what is the rate of change of temperature at the other face of the wall?