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. |
Time lag is given by the formula |
| A. | x/2 [1/ (α π n) ½]. |
| B. | x/3 [1/ (α π n) ½]. |
| C. | x/4 [1/ (α π n) ½]. |
| D. | x/5 [1/ (α π n) ½]. |
| Answer» B. x/3 [1/ (α π n) ½]. | |
| 2. |
Consider he above problem, find the rate of change of temperature at the inside surface of the tube |
| A. | – 35 degree Celsius/hour |
| B. | – 45 degree Celsius/hour |
| C. | – 55 degree Celsius/hour |
| D. | – 65 degree Celsius/hour |
| Answer» D. – 65 degree Celsius/hour | |
| 3. |
At a certain time instant, the temperature distribution in a long cylindrical fire tube can be represented approximately by the relationT = 650 + 800 r – 4250 r2Where temperature t is in degree Celsius and radius r is in meter. Find the rate of heat flow such that the tube measures: inside radius 25 cm, outside radius 40 cm and length 1.5 m.For the tube materialK = 5.5 W/m Kα = 0.004 m2/hr |
| A. | 3.672 * 10 8 W |
| B. | 3.672 * 10 2 W |
| C. | 3.672 * 10 5 W |
| D. | – 3.672 * 10 5 W |
| Answer» E. | |
| 4. |
A large plane wall, 40 cm thick and 8 m2 area, is heated from one side and temperature distribution at a certain time instant is approximately prescribed by the relationT = 80 – 60 x +12 x2 + 25 x3 – 20 x4Where temperature t is in degree Celsius and the distance x in meters. Make calculations for heat energy stored in the wall in unit time.For wall material:Thermal conductivity = 6 W/m K and thermal diffusivity = 0.02 m2/hr. |
| A. | 870.4 W |
| B. | 345.6 W |
| C. | 791.04 W |
| D. | 238.5 W |
| Answer» D. 238.5 W | |
| 5. |
The temperature distribution at a certain time instant through a 50 cm thick wall is prescribed by the relationT = 300 – 500 x – 100 x2 + 140 x3Where temperature t is in degree Celsius and the distance x in meters has been measured from the hot surface. If thermal conductivity of the wall material is 20 k J/m hr degree, calculate the heat energy stored per unit area of the wall |
| A. | 4100 k J/hr |
| B. | 4200 k J/hr |
| C. | 4300 k J/hr |
| D. | 4400 k J/hr |
| Answer» B. 4200 k J/hr | |
| 6. |
A single cylinder 2-stroke engine operates at 1500 rpm. Calculate the depth where the temperature wave due to variation in cylinder is damped to 1% of its surface value. For the cylinder material, thermal diffusivity = 0.042 m2/hr |
| A. | 0.1996 cm |
| B. | 0.3887 cm |
| C. | 0.2774 cm |
| D. | 0.1775 cm |
| Answer» E. | |
| 7. |
The temperature variation of a thick brick wall during periodic heating or cooling follows a sinusoidal waveform. During a period of 24 hours, the surface temperature ranges from 25 degree Celsius to 75 degree Celsius. Workout the time lag of the temperature wave corresponding to a point located at 25 cm from the wall surface. Thermo-physical properties of the wall material are; thermal conductivity = 0.62 W/m K; specific heat = 450 J/kg K and density = 1620 kg/m3 |
| A. | 3.980 hour |
| B. | 6.245 hour |
| C. | 2.648 hour |
| D. | 3.850 hour |
| Answer» C. 2.648 hour | |
| 8. |
TIME_LAG_IS_GIVEN_BY_THE_FORMULA?$ |
| A. | x/2 [1/ (α π n) <sup>½</sup>]. |
| B. | x/3 [1/ (α π n) <sup>½</sup>]. |
| C. | x/4 [1/ (α π n) <sup>½</sup>]. |
| D. | x/5 [1/ (α π n) <sup>½</sup>]. |
| Answer» B. x/3 [1/ (‚âà√≠¬¨¬± ‚âà√¨‚àö√ë n) <sup>¬¨¬®≈í¬©</sup>]. | |
| 9. |
CONSIDER_HE_ABOVE_PROBLEM,_FIND_THE_RATE_OF_CHANGE_OF_TEMPERATURE_AT_THE_INSIDE_SURFACE_OF_THE_TUBE?$ |
| A. | – 35 degree Celsius/hour |
| B. | – 45 degree Celsius/hour |
| C. | – 55 degree Celsius/hour |
| D. | – 65 degree Celsius/hour |
| Answer» D. ‚Äö√Ñ√∂‚àö√ë‚àö¬® 65 degree Celsius/hour | |
| 10. |
Consider the above problem, calculate rate of temperature change at 20 cm distance from the side being heated |
| A. | 0.777 degree Celsius/hour |
| B. | 0.888 degree Celsius/hour |
| C. | 0.999 degree Celsius/hour |
| D. | 0.666 degree Celsius/hour |
| Answer» C. 0.999 degree Celsius/hour | |
| 11. |
The temperature distribution at a certain time instant through a 50 cm thick wall is prescribed by the relation |
| A. | |
| B. | |
| Answer» B. | |
| 12. |
A single cylinder 2-stroke engine operates at 1500 rpm. Calculate the depth where the temperature wave due to variation in cylinder is damped to 1% of its surface value. For the cylinder material, thermal diffusivity = 0.042 m2/hr |
| A. | 0.1996 cm |
| B. | 0.3887 cm |
| C. | 0.2774 cm |
| D. | 0.1775 cm |
| Answer» E. | |
| 13. |
The temperature variation of a thick brick wall during periodic heating or cooling follows a sinusoidal waveform. During a period of 24 hours, the surface temperature ranges from 25 degree Celsius to 75 degree Celsius. Workout the time lag of the temperature wave corresponding to a point located at 25 cm from the wall surface. Thermo-physical properties of the wall material are; thermal conductivity = 0.62 W/m K; specific heat = 450 J/kg K and density = 1620 kg/m3 |
| A. | 3.980 hour |
| B. | 6.245 hour |
| C. | 2.648 hour |
| D. | 3.850 hour |
| Answer» C. 2.648 hour | |
| 14. |
The surface temperature oscillates about the mean temperature level in accordance with the relation |
| A. | α <sub>S,T</sub> – α <sub>S,A</sub> = 2 sin (2 π n T) |
| B. | α <sub>S,T</sub> – α <sub>S,A</sub> = 5 sin (2 π n T) |
| C. | α <sub>S,T</sub> – α <sub>S,A</sub> = sin (2 π n T) |
| D. | α <sub>S,T</sub> – α <sub>S,A</sub> = 3 sin (2 π n T) |
| Answer» D. ‚âà√≠¬¨¬± <sub>S,T</sub> ‚Äö√Ñ√∂‚àö√ë‚àö¬® ‚âà√≠¬¨¬± <sub>S,A</sub> = 3 sin (2 ‚âà√¨‚àö√ë n T) | |
| 15. |
When the surface temperature variation inside a solid are periodic in nature, the profile of temperature variation with time may assume |
| A. | Triangular |
| B. | Linear |
| C. | Parabolic |
| D. | Hyperbolic |
| Answer» B. Linear | |