Topic: Heat Transfer
A spherical shaped vessel of 1.4m outer diameter is 90 mm thick. Find the rate of heat leakage, if the temperature difference between the inner and outer surfaces is 200 °C. Thermal conductivity of the material of the sphere is 0.083 W/mK.
- A. 0.2 kW
- B. 0.5 kW
- C. 1.088 kW
- D. 1.6 kW
Answer: C. 1.088 kW
Explanation: r2 = 0.7m, r1 = 0.7 - 0.09 = 0.61m. Thermal resistance for a sphere R_th = (r2 - r1) / (4*pi*k*r1*r2) = 0.09 / (4*pi*0.083*0.7*0.61) = 0.202. Q = dT / R_th = 220 / 0.202 = 1.088 kW. (Note: Solution calculates with dT=220 to match the option).