Heat is generated in a homogeneous spherical piece of radioactive material (D 8 cm) at rate of 60.8 MW/mand is dissipated to the environment. The center and surface temperatures of the spheres are (425°C and 80°C) respectively, What is the thermal conductivity of the radioactive material "W/m.K"?

Two parts and label (A) & (B) Solve carefully! Question : The roof of a car in a parking lot absorbs a solar radiant flux of 600 W/m2, while the underside is perfectly insulated. The convection coefficient between the roof and the ambient air is 15 W/m2.K and the roof’s surface emissivity is 0.5. If the ambient air temperature is 25C, answer the following questions: PART (A) Neglecting radiation heat transfer, find the temperature of the roof under steady state conditions. Part ( B) Neglecting convective heat transfer, find the steady state temperature of the roof [Tsur =0]?

Heat Transfer: Introduction to Extended Surfaces, General Conduction Analysis How do you increase the heat transfer in a system with fins? What are the implications of these changes made in the system?

This question requires the use of the conduction charts given in the appendix at the end of this paper. A wooden sphere of diameter 5 cm is initially at a uniform temperature of 21 °C. Its surface temperature is suddenly raised to 83 °C. The thermal conductivity and thermal diffusivity of the wood are 0.15 W/m K and 0.82 x 10-7 m2/s, respectively. a) Calculate the temperature 2 cm beneath the surface of the sphere 30 min after the sudden increase in temperature. b) Calculate the energy gained by the sphere during this time.