MCQOPTIONS
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MCQOPTIONS
This section includes 15 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Transfer knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A stainless steel tube with inner diameter 12 mm, thickness 0.2 mm and length 50n cm is heated electrically. The entire 15 k W of heat energy generated in the tube is transferred through its outer surface. Find the intensity of the current flow |
| A. | 52 amps |
| B. | 62 amps |
| C. | 72 amps |
| D. | 82 amps |
| Answer» B. 62 amps | |
| 2. |
A cylindrical cement tube of radii 0.05 cm and 1.0 cm has a wire embedded into it along its axis. To maintain a steady temperature difference of 120 degree Celsius between the inner and outer surfaces, a current of 5 ampere is made to flow in the wire. Find the amount of heat generated per meter length. Take resistance of wire equal to 0.1 ohm per cm of length |
| A. | 150 W/m length |
| B. | 250 W/m length |
| C. | 350 W/m length |
| D. | 450 W/m length |
| Answer» C. 350 W/m length | |
| 3. |
For steady state and a constant value of thermal conductivity, the temperature distribution associated with radial convection through a cylinder is |
| A. | Linear |
| B. | Parabolic |
| C. | Logarithmic |
| D. | Exponential |
| Answer» D. Exponential | |
| 4. |
A cylinder of radius r and made of material of thermal conductivity k 1 is surrounded by a cylindrical shell of inner radius r and outer radius 2r. This outer shell is made of a material of thermal conductivity k 2. Net conductivity would be |
| A. | k 1 + 3 k 2/4 |
| B. | k 1 + k 2/4 |
| C. | k 1 + 3k 2 |
| D. | k 1 + k 2 |
| Answer» B. k 1 + k 2/4 | |
| 5. |
The heat flow equation through a cylinder of inner radius r1 and outer radius r2 is desired to be written in the same form as that for heat flow through a plane wall. For wall thickness (r 2-r 1) the area will be |
| A. | A1 + A2/2 |
| B. | A1 + A2 |
| C. | A2 – A1/ log e (A2/A1) |
| D. | A1 + A2/2 log e (A2/A1) |
| Answer» B. A1 + A2 | |
| 6. |
A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick of fiber glass insulation (k = 0.05 W/m degree). If the inside and outside convective coefficients are 10 W/m2 degree and 5 W/m2 degree, calculate the overall heat transfer coefficient based on inside diameter of pipe. In the diagram, the diameter of small circle is 20 mm |
| A. | 1.789 W/m2 degree |
| B. | 2.789 W/m2 degree |
| C. | 3.789 W/m2 degree |
| D. | 4.789 W/m2 degree |
| E. | . If the inside and outside convective coefficients are 10 W/m2 degree and 5 W/m2 degree, calculate the overall heat transfer coefficient based on inside diameter of pipe. In the diagram, the diameter of small circle is 20 mma) 1.789 W/m2 degreeb) 2.789 W/m2 degreec) 3.789 W/m2 degreed) 4.789 W/m2 degree |
| Answer» C. 3.789 W/m2 degree | |
| 7. |
A_STAINLESS_STEEL_TUBE_WITH_INNER_DIAMETER_12_MM,_THICKNESS_0.2_MM_AND_LENGTH_50N_CM_IS_HEATED_ELECTRICALLY._THE_ENTIRE_15_K_W_OF_HEAT_ENERGY_GENERATED_IN_THE_TUBE_IS_TRANSFERRED_THROUGH_ITS_OUTER_SURFACE._FIND_THE_INTENSITY_OF_THE_CURRENT_FLOW?$ |
| A. | 52 amps |
| B. | 62 amps |
| C. | 72 amps |
| D. | 82 amps |
| Answer» B. 62 amps | |
| 8. |
A_CYLINDRICAL_CEMENT_TUBE_OF_RADII_0.05_CM_AND_1.0_CM_HAS_A_WIRE_EMBEDDED_INTO_IT_ALONG_ITS_AXIS._TO_MAINTAIN_A_STEADY_TEMPERATURE_DIFFERENCE_OF_120_DEGREE_CELSIUS_BETWEEN_THE_INNER_AND_OUTER_SURFACES,_A_CURRENT_OF_5_AMPERE_IS_MADE_TO_FLOW_IN_THE_WIRE._FIND_THE_AMOUNT_OF_HEAT_GENERATED_PER_METER_LENGTH._TAKE_RESISTANCE_OF_WIRE_EQUAL_TO_0.1_OHM_PER_CM_OF_LENGTH?$ |
| A. | 150 W/m length |
| B. | 250 W/m length |
| C. | 350 W/m length |
| D. | 450 W/m length |
| Answer» C. 350 W/m length | |
| 9. |
For steady state and a constant value of thermal conductivity, the temperature distribution associated with radial convection through a cylinder i? |
| A. | Linear |
| B. | Parabolic |
| C. | Logarithmic |
| D. | Exponential |
| Answer» D. Exponential | |
| 10. |
A cylinder of radius r and made of material of thermal conductivity k 1 is surrounded by a cylindrical shell of inner radius r and outer radius 2r. This outer shell is made of a material of thermal conductivity k 2. Net conductivity would be |
| A. | k <sub>1</sub> + 3 k <sub>2</sub>/4 |
| B. | k <sub>1</sub> + k <sub>2</sub>/4 |
| C. | k <sub>1</sub> + 3k <sub>2</sub> |
| D. | k <sub>1</sub> + k <sub>2</sub> |
| Answer» B. k <sub>1</sub> + k <sub>2</sub>/4 | |
| 11. |
The heat flow equation through a cylinder of inner radius r1 and outer radius r2 is desired to be written in the same form as that for heat flow through a plane wall. For wall thickness (r 2-r 1) the area will be |
| A. | A<sub>1</sub> + A<sub>2</sub>/2 |
| B. | A<sub>1</sub> + A<sub>2</sub> |
| C. | A<sub>2</sub> – A<sub>1</sub>/ log <sub>e </sub>(A<sub>2</sub>/A<sub>1</sub>) |
| D. | A<sub>1</sub> + A<sub>2</sub>/2 log <sub>e </sub>(A<sub>2</sub>/A<sub>1</sub>) |
| Answer» B. A<sub>1</sub> + A<sub>2</sub> | |
| 12. |
A hot fluid is being conveyed through a long pipe of 4 cm outer diameter and covered with 2 cm thick insulation. It is proposed to reduce the conduction heat loss to the surroundings to one-third of the present rate by further covering with same insulation. Calculate the additional thickness of insulation |
| A. | 11 cm |
| B. | 12 cm |
| C. | 13 cm |
| D. | 14 cm |
| Answer» C. 13 cm | |
| 13. |
Logarithmic mean area of the cylindrical tube is given as |
| A. | 2πr <sub>m</sub> |
| B. | πr <sub>m</sub>l |
| C. | 2πr <sub>m</sub>l |
| D. | 2r <sub>m</sub>l |
| Answer» D. 2r <sub>m</sub>l | |
| 14. |
The rate of heat conduction through a cylindrical tube is usually expressed as |
| A. | Per unit length |
| B. | Per unit area |
| C. | Only length |
| D. | Only area |
| Answer» B. Per unit area | |
| 15. |
Typical examples of heat conduction through cylindrical tubes are not found in |
| A. | Power plants |
| B. | Oil refineries |
| C. | Most process industries |
| D. | Aircrafts |
| Answer» E. | |