Heat Transfer Practice Test 2

1. For a plane wall of thickness l with uniformly distributed heat generation q _g per unit volume, the temperature t ₀ at mid plane is given by

2. The temperature distribution profile for a solid cylinder is

3. The rear window of an automobile is made of thick glass i.e. AB = 5 mm and thermal conductivity is 0.8 W/m degree. To defrost this window, a thin transparent film type heating element has been fixed to its inner surface. For the conditions given below, determine the electric power that must be provided per unit area of window if a temperature 5 degree Celsius is maintained at its outer surface. Interior air temperature and the corresponding surface coefficient are 20 degree Celsius and 12 W/m² degree. Surrounding air temperature and the corresponding surface coefficient are – 15 degree Celsius and 70 W/m² degree. Electric heater provides uniform heat flux

4. A solid sphere of 8 cm radius has a uniform heat generation 0f 4000000 W/m³. The outside surface is exposed to a fluid at 150 degree Celsius with convective heat transfer coefficient of 750 W/m² K. If thermal conductivity of the solid material is 30 W/m K, determine maximum temperature

5. The shape factor for complete rectangular furnace is
Where a, b and c are the inside dimensions and d x is the wall thickness

6. Which is true regarding a complete rectangular furnace?

7. In convection from the tip, we introduced a factor known as

8. For an object i.e. spherical the value of critical radius would be

9. The general solution of linear and homogenous differential equation (second form) is of the form

10. The value of critical radius in case of a cylindrical hollow object is