Question

1 Item 1 Item 1 1.25 points circular ceramic plate that can be modeled as a blackbody is being heated by an electrical heater. The plate is 30 cm in diameter and is situated in a surrounding ambient temperature of 15°C where the natural convection heat transfer coefficient is 12 W/m2·K. If the efficiency of the electrical heater to transfer heat to the plate is 80%, determine the electric power that the heater needs to keep the surface temperature of the plate at 180°C

Answer 1

Answer:

174.85 W

Explanation:

Area of plate = 3.14 x (15x 10⁻²)²

= 706.5 x 10⁻⁴ m²

heat being radiated by convection = 12 x 706.5 x 10⁻⁴ ( 180 - 15 )

= 139.88 W. This energy needs to be fed by heat source to maintain a constant temperature of 180 degree.

If power of electric source is P

P x .8 = 139.88

P = 139.88 / .8

= 174.85 W