MCQOPTIONS
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MCQOPTIONS
This section includes 14 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. |
Determine the exit pressure of steam if the steam enters a nozzle at 11 bar and 300 C. At the outlet it is observed that the specific volume of the steam is 0.86804 m3/kg. The expansion of steam is metastable. |
| A. | 4 bar |
| B. | 3 bar |
| C. | 2 bar |
| D. | 1 bar |
| Answer» D. 1 bar | |
| 2. |
Which of the following is NOT an effect of supersaturation in steam flowing through a convergent-divergent nozzle? |
| A. | Increase in specific volume of steam |
| B. | Increase in the entropy of steam |
| C. | Improvement in dryness fraction |
| D. | Increase in the enthalpy drop |
| Answer» E. | |
| 3. |
The point on the h-s diagram at which the condensation beings and normal conditions of thermal equilibrium are restored is said to be on _____ |
| A. | wilson line |
| B. | saturation vapor curve |
| C. | constant dryness fraction line |
| D. | constant pressure line |
| Answer» B. saturation vapor curve | |
| 4. |
Which of the following statement about metastable expansion of steam through a steam nozzle is FALSE? |
| A. | It increases the discharge through the nozzle |
| B. | Steam is undercooled to a temperature less than that corresponding to its pressure |
| C. | Density of steam is increased |
| D. | Exit velocity of the steam is increased |
| Answer» E. | |
| 5. |
What is the value of index of expansion for supersaturated steam. (Pvn=C, n is the index of expansion) |
| A. | 1.300 |
| B. | 1.013 |
| C. | 1.135 |
| D. | 1.000 |
| Answer» B. 1.013 | |
| 6. |
Steam at 15 bar pressure and 250 C enters a convergent-divergent steam nozzle and leaves at 4 bar. The mass flow rate is 5 kg/s. Calculate the exit area of the nozzle if the expansion is metastable. |
| A. | 0.00542187 m<sup>2</sup> |
| B. | 0.0029147 m<sup>2</sup> |
| C. | 0.036521 m<sup>2</sup> |
| D. | 0.003265 m<sup>2</sup> |
| Answer» C. 0.036521 m<sup>2</sup> | |
| 7. |
Calculate the degree of supersaturation if steam at 10 bar 250 C is discharged at 2 bar by a convergent-divergent nozzle. Consider metastable steam expansion and negligible inlet velocity. |
| A. | 5.65 |
| B. | 3.11 |
| C. | 2.15 |
| D. | 2.36 |
| Answer» C. 2.15 | |
| 8. |
Steam at 20 bar and 300 C enters a convergent-divergent steam nozzle and is discharged at 3 bar. Considering the effects of supersaturation calculate the degree of undercooling. |
| A. | 36.65 C |
| B. | 45.54 C |
| C. | 23.32 C |
| D. | 62.87 C |
| Answer» B. 45.54 C | |
| 9. |
Steam at 12 bar and 300 C enters a convergent-divergent steam nozzle and leaves at 3 bar. If the expansion of the steam is metastable, calculate the supercooled temperature. |
| A. | 165 C |
| B. | 143 C |
| C. | 154 C |
| D. | 120 C |
| Answer» C. 154 C | |
| 10. |
Which of the following is the correct formula for calculating the supercooled temperature of steam, when steam metastable expansion of steam takes place inside a steam nozzle. (T2 Supercooled temperature, T1 Inlet temperature of steam) |
| A. | ( frac{T_2}{T_1} = ( frac{P_2}{P_1})^ frac{n}{n-1} ) |
| B. | ( frac{T_2}{T_1} = ( frac{P_2}{P_1})^ frac{n+1}{n} ) |
| C. | ( frac{T_2}{T_1} = ( frac{P_1}{P_2})^ frac{n}{n-1} ) |
| D. | ( frac{T_2}{T_1} = ( frac{P_2}{P_1})^ frac{n}{n-1} ) |
| Answer» E. | |
| 11. |
Calculate the enthalpy drop steam enters a convergent-divergent nozzle at 11 bar and 250 C and leaves at 1 bar. The expansion is to be considered metastable. |
| A. | 427031.34 kJ/kg |
| B. | 55648.32 kJ/kg |
| C. | 323654.25 kJ/kg |
| D. | 158469.21 kJ/kg |
| Answer» B. 55648.32 kJ/kg | |
| 12. |
The sudden expansion of dry saturated steam in the absence of dust, doesn t lead to condensation until its density is about 8 times that of the saturated vapor of the same pressure. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 13. |
Considering metastable expansion to be in effect, the flow of wet steam though a convergent-divergent nozzle shall result in a discharge slightly less than the calculated one. |
| A. | True |
| B. | False |
| Answer» C. | |
| 14. |
What is Wilson line? |
| A. | It is an isothermal line, at which the condensation completes |
| B. | Saturation line of water is also called Wilson line |
| C. | It represents the limiting condition of undercooling at which the condensation begins |
| D. | It represents an Isobaric line, at which the condensation commences |
| Answer» D. It represents an Isobaric line, at which the condensation commences | |