Heat Transfer Practice Test 1

1. Choose the false statement

2. Thermal conductivity is defined as the heat flow per unit time

3. Consider system A at uniform temperature t and system B at another uniform temperature T (t > T). Let the two systems be brought into contact and be thermally insulated from their surroundings but not from each other. Energy will flow from system A to system B because of

4. Which one of the following forms of water have the highest value of thermal conductivity?

5. Which of the following is an example of forced convection?

6. A composite wall is made of two layers of thickness δ₁ and δ₂ having thermal conductivities k and 2k and equal surface area normal to the direction of heat flow. The outer surface of composite wall are at 100 degree Celsius and 200 degree Celsius. The minimum surface temperature at the junction is 150 degree Celsius. What will be the ratio of wall thickness?

7. The thermal resistance for heat conduction through a spherical wall is

8. Heat transfer in a long, hollow cylinder which is maintained at uniform but different temperatures on its inner and outer surfaces may be assumed to be taking place in which direction?

9. Let us assume two walls of same thickness and cross-sectional area having thermal conductivities in the ratio 1/2. Let us say there is same temperature difference across the wall faces, the ratio of heat flow will be

10. The quantity d t/Q for conduction of heat through a body i.e. spherical in shape is