MCQOPTIONS
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MCQOPTIONS
This section includes 17 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. |
Air at 20 degree Celsius flows over a flat surface maintained at 80 degree Celsius. The local heat flow at a point was measured as 1250 W/m2 .Take thermal conductivity of air as 0.028 W/m K, calculate the temperature at a distance 0.5 mm from the surface |
| A. | 57.682 degree celsius |
| B. | 67.682 degree celsius |
| C. | 77.682 degree celsius |
| D. | 87.682 degree celsius |
| Answer» B. 67.682 degree celsius | |
| 2. |
The temperature profile at a particular location on a surface is prescribed by the identity(t s – t) / (t s – t infinity) = (1/2) (y/0.0075) 3 + (3/2) (y/0.0075)If thermal conductivity of air is stated to be 0.03 W/m K, determine the value of convective heat transfer coefficient |
| A. | 4 W/m2 K |
| B. | 5 W/m2 K |
| C. | 6 W/m2 K |
| D. | 7 W/m2 K |
| Answer» D. 7 W/m2 K | |
| 3. |
Consider the above problem, make calculations for the rate of heat dissipation from the cylinder fins by convection when motor cycle is moving at 60 km/hr and convective coefficient is 75 W/m2 K |
| A. | 9640 W |
| B. | 9540 W |
| C. | 9440 W |
| D. | 9340 W |
| Answer» C. 9440 W | |
| 4. |
A motor cycle cylinder consists of ten fins, each 150 mm outside diameter and 75 mm inside diameter. The average fin temperature is 500 degree Celsius and the surrounding air is at 20 degree Celsius temperature. Make calculations for the rate of heat dissipation from the cylinder fins by convection when motor cycle is stationary and convective coefficient is 6 W/m2 K |
| A. | 432.2 W |
| B. | 532.2 W |
| C. | 632.2 W |
| D. | 763.2 W |
| Answer» E. | |
| 5. |
Thermo-physical properties of the fluid are represented by(i) Density(ii) Viscosity(iii) Specific heat(iv) Thermal conductivityIdentify the correct option |
| A. | i and ii |
| B. | i, ii, iii and iv |
| C. | ii, iii and iv |
| D. | i, ii and iii |
| Answer» C. ii, iii and iv | |
| 6. |
Forced air flows over a convection heat exchanger in a room heater, resulting in a convective heat transfer coefficient 1.136 k W/m2 K. The surface temperature of heat exchanger may be considered constant at 65 degree Celsius, and the air is at 20 degree Celsius. Determine the heat exchanger surface area required for 8.8 k W of heating |
| A. | 0.272 m2 |
| B. | 0.472 m2 |
| C. | 0.172 m2 |
| D. | 0.672 m2 |
| Answer» D. 0.672 m2 | |
| 7. |
The value of film coefficient is dependent upon(i) Boundary layer configuration(ii) Geometry and orientation of the surface(iii) Surface conditions |
| A. | i and ii |
| B. | ii and iii |
| C. | i and ii |
| D. | i, ii and iii |
| Answer» E. | |
| 8. |
THE_TEMPERATURE_PROFILE_AT_A_PARTICULAR_LOCATION_ON_A_SURFACE_IS_PRESCRIBED_BY_THE_IDENTITY?$ |
| A. | / (t <sub>s</sub> – t<sub> infinity</sub>) = (1/2) (y/0.0075) <sup>3 </sup>+ (3/2) (y/0.0075) |
| B. | |
| C. | 4 W/m<sup>2 </sup>K |
| Answer» D. | |
| 9. |
Air_at_20_degree_Celsius_flows_over_a_flat_surface_maintained_at_80_degree_Celsius._The_local_heat_flow_at_a_point_was_measured_as_1250_W/m2_.Take_thermal_conductivity_of_air_as_0.028_W/m_K,_calculate_the_temperature_at_a_distance_0.5_mm_from_the_surface$ |
| A. | 57.682 degree celsius |
| B. | 67.682 degree celsius |
| C. | 77.682 degree celsius |
| D. | 87.682 degree celsius |
| Answer» B. 67.682 degree celsius | |
| 10. |
Consider the above problem, make calculations for the rate of heat dissipation from the cylinder fins by convection when motor cycle is moving at 60 km/hr and convective coefficient is 75 W/m2 ? |
| A. | 9640 W |
| B. | 9540 W |
| C. | 9440 W |
| D. | 9340 W |
| Answer» C. 9440 W | |
| 11. |
A motor cycle cylinder consists of ten fins, each 150 mm outside diameter and 75 mm inside diameter. The average fin temperature is 500 degree Celsius and the surrounding air is at 20 degree Celsius temperature. Make calculations for the rate of heat dissipation from the cylinder fins by convection when motor cycle is stationary and convective coefficient is 6 W/m2 K |
| A. | 432.2 W |
| B. | 532.2 W |
| C. | 632.2 W |
| D. | 763.2 W |
| Answer» E. | |
| 12. |
Thermo-physical properties of the fluid are represented by |
| A. | Density |
| B. | Viscosity |
| C. | Specific heat |
| D. | Thermal conductivity |
| Answer» C. Specific heat | |
| 13. |
A region of fluid motion near a plate in which temperature gradient exist is |
| A. | Thermal boundary layer |
| B. | Diathermia boundary layer |
| C. | Turbulent flow |
| D. | Laminar flow |
| Answer» B. Diathermia boundary layer | |
| 14. |
Forced air flows over a convection heat exchanger in a room heater, resulting in a convective heat transfer coefficient 1.136 k W/m2 K. The surface temperature of heat exchanger may be considered constant at 65 degree Celsius, and the air is at 20 degree Celsius. Determine the heat exchanger surface area required for 8.8 k W of heating |
| A. | 0.272 m<sup>2</sup> |
| B. | 0.472 m<sup>2</sup> |
| C. | 0.172 m<sup>2</sup> |
| D. | 0.672 m<sup>2</sup> |
| Answer» D. 0.672 m<sup>2</sup> | |
| 15. |
The convection coefficients for boiling and condensation lie in the range |
| A. | 5000-12500 W/m<sup> 2 </sup>K |
| B. | 2500-100000 W/m<sup> 2 </sup>K |
| C. | 2500-5000 W/m<sup> 2 </sup>K |
| D. | 2500-12500 W/m<sup> 2 </sup>K |
| Answer» C. 2500-5000 W/m<sup> 2 </sup>K | |
| 16. |
The value of film coefficient is dependent upon |
| A. | Boundary layer configuration |
| B. | Geometry and orientation of the surface |
| C. | Surface conditions |
| D. | i and ii |
| Answer» E. | |
| 17. |
Newton-Rikhman law is given by |
| A. | Q = h A (t <sub>s</sub> – t<sub> f</sub>) |
| B. | Q = 2 h A (t <sub>s</sub> – t<sub> f</sub>) |
| C. | Q = 3 h A (t <sub>s</sub> – t<sub> f</sub>) |
| D. | Q = 4 h A (t <sub>s</sub> – t<sub> f</sub>) |
| Answer» B. Q = 2 h A (t <sub>s</sub> ‚Äö√Ñ√∂‚àö√ë‚àö¬® t<sub> f</sub>) | |