MCQOPTIONS
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MCQOPTIONS
This section includes 15 Mcqs, each offering curated multiple-choice questions to sharpen your Thermal Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Dry and saturated steam at 11 bar pressure enters a convergent-divergent nozzle and is discharged at 2 bar. Determine the actual enthalpy drop if he efficiency of the nozzle is 96%. |
| A. | 254.56 kJ/kg |
| B. | 321.32 kJ/kg |
| C. | 288.14 kJ/kg |
| D. | 245.63 kJ/kg |
| Answer» D. 245.63 kJ/kg | |
| 2. |
Choose the most appropriate statement regarding velocity coefficient. |
| A. | It can be zero |
| B. | It can be greater than one |
| C. | It should strictly lie between zero and one |
| D. | It is square of nozzle efficiency |
| Answer» D. It is square of nozzle efficiency | |
| 3. |
Steam at 14 bar and 250°C enters a convergent-divergent steam nozzle and is discharged at 2 bar. Determine the nozzle efficiency if the velocity coefficient is 0.95. Neglect the initial velocity of steam. |
| A. | 95.65% |
| B. | 90.25% |
| C. | 99.65% |
| D. | 85.32% |
| Answer» C. 99.65% | |
| 4. |
A convergent-divergent steam nozzle is supplied with steam at 15 bar. It discharges the steam at 1 bar. Determine the exit velocity if the velocity coefficient of the given nozzle is 0.95. |
| A. | 785.42 m/s |
| B. | 654.32 m/s |
| C. | 908.90 m/s |
| D. | 854.65 m/s |
| Answer» D. 854.65 m/s | |
| 5. |
Nozzle efficiency is the ratio of isentropic enthalpy drop to actual enthalpy drop, between the same pressures. |
| A. | True |
| B. | False |
| Answer» C. | |
| 6. |
Find the mass flow rate if dry and saturated steam at 12 bar pressure is discharged at 2 bar by a convergent-divergent nozzle. The nozzle efficiency and exit area of the nozzle are 95% and 0.00256 m2. |
| A. | 1.5 kg/s |
| B. | 2.5 kg/s |
| C. | 3.0 kg/s |
| D. | 4.0 kg/s |
| Answer» C. 3.0 kg/s | |
| 7. |
Steam at 10 bar superheated to 200°C enters a convergent-divergent steam nozzles and leaves at 2 bar. Determine the dryness fraction of the steam discharged if the nozzle efficiency is 93%. |
| A. | 0.931 |
| B. | 0.865 |
| C. | 0.758 |
| D. | 0.963 |
| Answer» B. 0.865 | |
| 8. |
Dry and saturated steam at 10 bar enters a convergent-divergent nozzle and leaves at 1 bar. If 8% of heat drop is lost in friction find the percentage decrease in final velocity. Neglect initial velocity. |
| A. | 5.65% |
| B. | 3.87% |
| C. | 2.14% |
| D. | 4.08% |
| Answer» E. | |
| 9. |
Dry and saturated steam enters a convergent-divergent steam nozzle at 11 bar and leaves at 3 bar. Determine the nozzle efficiency if the actual enthalpy drop is 200 kJ/kg. |
| A. | 78.56% |
| B. | 96.36% |
| C. | 90.35% |
| D. | 85.27% |
| Answer» E. | |
| 10. |
Initial velocity of the steam entering a convergent-divergent steam nozzle is 60 m/s. Steam expands from 15 bar and 250°C to 1 bar. Determine the exit velocity of steam if nozzle has an efficiency of 95%. |
| A. | 973.08 m/s |
| B. | 654.32 m/s |
| C. | 785.45 m/s |
| D. | 900.75 m/s |
| Answer» B. 654.32 m/s | |
| 11. |
Dry and saturated steam at 12 bar expands through a convergent-divergent nozzle having 90% efficiency to 2 bar. Determine the actual exit velocity of the steam. Neglect the initial velocity of steam. |
| A. | 451.20 m/s |
| B. | 754.62 m/s |
| C. | 650.32 m/s |
| D. | 856.96 m/s |
| Answer» C. 650.32 m/s | |
| 12. |
Determine the velocity coefficient if the efficiency of a convergent-divergent steam nozzle is 92%. The inlet velocity of steam is negligible. |
| A. | 0.959 |
| B. | 0.120 |
| C. | 0.465 |
| D. | 0.542 |
| Answer» B. 0.120 | |
| 13. |
Presence of friction in a convergent-divergent nozzle, decreases the final velocity of the steam and increases the dryness fraction of the steam. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 14. |
Which of the following is NOT an effect of frictional loses in a convergent-divergent nozzle? |
| A. | Enthalpy drop is increased |
| B. | The expansion is not isentropic |
| C. | The final dryness fraction of the steam is increased |
| D. | The specific volume of steam is increased |
| Answer» B. The expansion is not isentropic | |
| 15. |
The final velocity obtained after passing the steam through a nozzle is less than the calculated one. Which of the following is NOT a valid reason for the same? |
| A. | Friction between steam and nozzle surface |
| B. | Steam not being superheated |
| C. | Shock loses |
| D. | Internal friction of steam |
| Answer» C. Shock loses | |