MCQOPTIONS
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MCQOPTIONS
This section includes 25 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. |
On a heat transfer surface, fins are provided to |
| A. | Increase turbulence in flow for enhancing heat transfer |
| B. | Increase temperature gradient so as to enhance heat transfer |
| C. | Pressure drop of the fluid should be minimized |
| D. | Surface area is maximum to promote the rate of heat transfer |
| Answer» E. | |
| 2. |
A steel rod (k = 30 W/m degree) 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and t a = 30 degree Celsius. Calculate the rate of heat dissipation |
| A. | 2.658 W |
| B. | 3.658 W |
| C. | 4.658 W |
| D. | 5.658 W |
| E. | 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and t a = 30 degree Celsius. Calculate the rate of heat dissipationa) 2.658 Wb) 3.658 Wc) 4.658 Wd) 5.658 W |
| Answer» C. 4.658 W | |
| 3. |
In order to achieve maximum heat dissipation, the fin should be designed in such a way that has a |
| A. | Maximum lateral surface towards the tip side of fin |
| B. | Minimum lateral surface near the center line |
| C. | Maximum lateral surface at the root side of fin |
| D. | Maximum lateral surface near the center of fin |
| Answer» D. Maximum lateral surface near the center of fin | |
| 4. |
A steel rod (k = 30 W/m degree) 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and t a = 30 degree Celsius. Calculate the fin efficiency |
| A. | 56.57% |
| B. | 66.57% |
| C. | 76.57% |
| D. | 86.57% |
| E. | 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and t a = 30 degree Celsius. Calculate the fin efficiencya) 56.57%b) 66.57%c) 76.57%d) 86.57% |
| Answer» C. 76.57% | |
| 5. |
It is said that fins can take a variety of forms(i) Longitudinal fins of rectangular cross section attached to a wall(ii) Cylindrical tubes with radial fins(iii) Conical rod protruding from a wallIdentify the correct statement |
| A. | i only |
| B. | i and ii |
| C. | ii and iii |
| D. | i, ii and iii |
| Answer» E. | |
| 6. |
Common applications of finned surfaces are with(i) Electrical motors(ii) Economizers for steam power plant(iii) Convectors for steam and cold water heating systems(iv) Cooling coilsIdentify the correct option |
| A. | i, ii and iv |
| B. | i, ii and iii |
| C. | i, ii, iii and iv |
| D. | i and ii |
| Answer» B. i, ii and iii | |
| 7. |
A very long copper rod 20 mm in diameter extends horizontally from a plane heated wall maintained at 100 degree Celsius. The surface of the rod is exposed to an air environment at 20 degree Celsius with convective heat transfer coefficient of 8.5 W/m2 degree. Workout the heat loss if the thermal conductivity of copper is 400 W/m degree |
| A. | 10.71 W |
| B. | 20.71 W |
| C. | 30.71 W |
| D. | 40.71 W |
| Answer» C. 30.71 W | |
| 8. |
A plate fin of length L = 1.5 cm and thickness 2 mm has efficiency of____ (if k = 210 W/m-K, h = 285 W/m2K) |
| A. | 84.1% |
| B. | 87.2% |
| C. | 89.9% |
| D. | 92.4% |
| Answer» D. 92.4% | |
| 9. |
An infinitely long pin fin, attached to an isothermal hot surface, transfers heat at a steady rate of Q̇1 to the ambient air. If the thermal conductivity of the fin material is doubled, while keeping everything else constant, the rate of steady-state heat transfer from the fin becomes Q̇2. The ratio Q̇2/Q̇1 is |
| A. | \(\dfrac{1}{\sqrt{2}}\) |
| B. | \(\dfrac{1}{2}\) |
| C. | 2 |
| D. | \(\sqrt{2}\) |
| Answer» E. | |
| 10. |
A fin has 5 mm diameter and 100 mm length. The thermal conductivity of fin material is 400 Wm-1K-1. One end of the fin is maintained at 130ºC and its remaining surface is exposed to ambient air at 30ºC. If the convective heat transfer coefficient is 40 Wm-2k-1, the heat loss (in W) from the fin is |
| A. | 0.08 |
| B. | 5 |
| C. | 7 |
| D. | 7.8 |
| Answer» C. 7 | |
| 11. |
A fin of length l protrudes from a surface held at temperature T0; it being higher than the ambient temperature Ta. The heat dissipation from the free end of the fin is stated to be negligibly small. What is the temperature gradient \((\frac {dT}{dx})_{x=L}\) at the tip of the fin? |
| A. | Zero |
| B. | \(\frac {T_0 -T_l}{l}\) |
| C. | h(T0 - Ta) |
| D. | \(\frac {T_l -T_a}{T_0 -T_a}\) |
| Answer» B. \(\frac {T_0 -T_l}{l}\) | |
| 12. |
Insulated tip temperature of a rectangular longitudinal fin will be equal to |
| A. | θotanh ml |
| B. | θosinh ml |
| C. | \(\frac{(\theta_otanh\;ml)}{ml}\) |
| D. | \(\frac{\theta_o}{cosh\;ml}\) |
| Answer» E. | |
| 13. |
Fins are provided on heat transferring surface in order to increase: |
| A. | Heat transfer area |
| B. | Heat transfer coefficient |
| C. | Temperature gradient |
| D. | Mechanical strength of the equipment |
| E. | All of the above |
| Answer» B. Heat transfer coefficient | |
| 14. |
Consider the following statement pertaining to large heat transfer rate using fins:1. fins should be used on the side where the heat transfer coefficient is small.2. long and thick fins should be used3. Short and thin fins should be used4. Thermal conductivity of fin material should be large.Of these |
| A. | 1,2 & 3 are correct |
| B. | 1,2 & 4 are correct |
| C. | 2,3 & 4 are correct |
| D. | 1,3 & 4 are correct |
| Answer» E. | |
| 15. |
A 3 cm long, 2 mm × 2 mm rectangular cross-section aluminium fin [k = 237 W/m°c] is attached to a surface. If the fin efficiency is 65%, the effectiveness of this single fin is: |
| A. | 30 |
| B. | 24 |
| C. | 8 |
| D. | 39 |
| Answer» E. | |
| 16. |
Consider the following statements:An increase in pin fin effectiveness is caused by high value of1. Convective coefficient2. Thermal conductivity3. Sectional area4. CircumferenceWhich of the above statements are correct? |
| A. | 1 and 3 |
| B. | 1 and 4 |
| C. | 2 and 3 |
| D. | 2 and 4 |
| Answer» E. | |
| 17. |
A_STEEL_ROD_(K_=_30_W/M_DEGREE)_1_CM_IN_DIAMETER_AND_5_CM_LONG_PROTRUDES_FROM_A_WALL_WHICH_IS_MAINTAINED_AT_10_DEGREE_CELSIUS._THE_ROD_IS_INSULATED_AT_ITS_TIP_AND_IS_EXPOSED_TO_AN_ENVIRONMENT_WITH_H_=_50_W/M2_DEGREE_AND_T_A_=_30_DEGREE_CELSIUS._CALCULATE_THE_RATE_OF_HEAT_DISSIPATION?$ |
| A. | 2.658 W |
| B. | 3.658 W |
| C. | 4.658 W |
| D. | 5.658 W |
| Answer» C. 4.658 W | |
| 18. |
On_a_heat_transfer_surface,_fins_are_provided_to$ |
| A. | Increase turbulence in flow for enhancing heat transfer |
| B. | Increase temperature gradient so as to enhance heat transfer |
| C. | Pressure drop of the fluid should be minimized |
| D. | Surface area is maximum to promote the rate of heat transfer |
| Answer» E. | |
| 19. |
In order to achieve maximum heat dissipation, the fin should be designed in such a way that has ? |
| A. | Maximum lateral surface towards the tip side of fin |
| B. | Minimum lateral surface near the center line |
| C. | Maximum lateral surface at the root side of fin |
| D. | Maximum lateral surface near the center of fin |
| Answer» D. Maximum lateral surface near the center of fin | |
| 20. |
If heat dissipation for one fin is given by 377.45 k J/hour, then what is the heat dissipation for 12 fins? |
| A. | 7529.4 k J/hour |
| B. | 6529.4 k J/hour |
| C. | 5529.4 k J/hour |
| D. | 4529.4 k J/hour |
| Answer» E. | |
| 21. |
If the fin is sufficiently thin, so heat flows pertain to |
| A. | One dimensional heat conduction |
| B. | Two dimensional heat conduction |
| C. | Three dimensional heat conduction |
| D. | No heat flow is there |
| Answer» B. Two dimensional heat conduction | |
| 22. |
A steel rod (k = 30 W/m degree) 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and t a = 30 degree Celsius. Calculate the fin efficiency |
| A. | 56.57% |
| B. | 66.57% |
| C. | 76.57% |
| D. | 86.57% |
| Answer» C. 76.57% | |
| 23. |
The extended surface used for the enhancement of heat dissipation is |
| A. | Convective coefficient |
| B. | Fourier number |
| C. | Fin |
| D. | No finned surface |
| Answer» D. No finned surface | |
| 24. |
Common applications of finned surfaces are with |
| A. | Electrical motors |
| B. | Economizers for steam power plant |
| C. | Convectors for steam and cold water heating systems |
| D. | Cooling coils |
| Answer» B. Economizers for steam power plant | |
| 25. |
A very long copper rod 20 mm in diameter extends horizontally from a plane heated wall maintained at 100 degree Celsius. The surface of the rod is exposed to an air environment at 20 degree Celsius with convective heat transfer coefficient of 8.5 W/m2 degree. Workout the heat loss if the thermal conductivity of copper is 400 W/m degree |
| A. | 10.71 W |
| B. | 20.71 W |
| C. | 30.71 W |
| D. | 40.71 W |
| Answer» C. 30.71 W | |