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. |
Assuming same efficiency for the same draught and neglecting leakage, power required by induced draught fan is greater than power required by forced draught fan. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2. |
A motor of power 4 kW is used to drive a forced draught fan. The draught obtained is 45 mm of water. The temperature of the flue gases leaving the boiler is 300 C. The mass of air supplied per kg of fuel is 15 kg. The volume of air at N.T.P. is 0.7734 m3. The coal consumption rate is 1960 kg/hr. Calculate the ambient temperature if the efficiency of the fan is 78%. |
| A. | 25 C |
| B. | 32 C |
| C. | 27 C |
| D. | 30 C |
| Answer» C. 27 C | |
| 3. |
A motor of power 8.7 kW is used to run an induced draught fan which maintains a draught of 50 mm of water. 19 kg of air is supplied for complete combustion of 1 kg of fuel. The temperature of hot gases 325 C. The efficiency of the fan is 85%. Determine the coal consumption rate. (Take V0 = 0.7734 m3) |
| A. | 1523 kg/hr |
| B. | 1465 kg/hr |
| C. | 1686 kg/hr |
| D. | 1785 kg/hr |
| Answer» D. 1785 kg/hr | |
| 4. |
Which of the following is FALSE about steam jet draught? |
| A. | Low grade fuel can also be used |
| B. | Requires low maintenance |
| C. | Steam jet draught is a type of artificial draught |
| D. | In case of forced steam jet draught, the jet is directed into smoke box |
| Answer» E. | |
| 5. |
The temperature of the flue gases leaving the boiler is 330 C and the ambient temperature is 27 C. Find the power required by an induced draught fan if the power required by a forced draught fan under the same circumstances (same efficiency) is 3.6 kW. |
| A. | 7.24 kW |
| B. | 8.54 kW |
| C. | 5.78 kW |
| D. | 4.27 kW |
| Answer» B. 8.54 kW | |
| 6. |
Determine the ratio of power required to run a forced draught fan to power required to run an induced draught fan, considering same efficiency and same draught. The ambient temperature and temperature of flue gases leaving the boiler are 28 C and 300 C respectively. The coal consumption rate and mass of air supplied for complete combustion of fuel are also same. |
| A. | 0.52 |
| B. | 0.23 |
| C. | 0.65 |
| D. | 0.78 |
| Answer» B. 0.23 | |
| 7. |
A motor which runs an induced draught fan, maintains a constant draught of 55 mm of water. The efficiency of the fan is 91%. The ambient temperature is 30 C and the temperature of the flue gases leaving the boiler is 330 C. The coal consumption rate is 1850 kg/hr. The volume of air at N.T.P. should be taken as 0.7734 m3. Find the power of the motor if 20 kg of air is required for complete combustion of 1 kg of fuel. |
| A. | 4.65 kW |
| B. | 7.69 kW |
| C. | 12.65 kW |
| D. | 10.41 kW |
| Answer» E. | |
| 8. |
A motor rated 5 kW runs a forced draught fan. It maintains a constant draught of 50 mm of water. Mass of air supplied per kg of fuel is 18 kg. Determine the efficiency of the fan is the ambient temperature is 27 C and 1500 kg of coal is consumed per hour respectively. (Take V0 = 0.7734 m3) |
| A. | 63% |
| B. | 78% |
| C. | 84% |
| D. | 59% |
| Answer» B. 78% | |
| 9. |
Calculate power of motor required to drive a forced draught fan which maintains a draught of 45 mm of water the temperatures of flue gases leaving the boiler and air inside the boiler house are 300 C and 25 C respectively. It is given that the air supplied for complete combustion of 1 kg of fuel is 20 kg. 1800 kg of coal is burnt per hour. The efficiency of the fan is 80%. (Take Volume of air at N.T.P as 0.7734 m3) |
| A. | 9.56 kW |
| B. | 4.66 kW |
| C. | 5.65 kW |
| D. | 6.32 kW |
| Answer» C. 5.65 kW | |
| 10. |
Which of the following statements is FALSE regarding artificial draught? |
| A. | There is no need of water cooled bearing in forced draught fan |
| B. | Fan size and power required by a forced draught fan are 1/5 to of that required for an induced draught fan |
| C. | Tendency for air leak into the boiler furnace is less in Induced draught fan as compared to forced draught fan |
| D. | In forced draught the fan/blower is installed near the base of the boiler |
| Answer» D. In forced draught the fan/blower is installed near the base of the boiler | |
| 11. |
Which of the following statement is TRUE about balanced draught? |
| A. | No fan/blower is installed |
| B. | A fan/blower is installed in the middle of the chimney |
| C. | One fan/blower is installed at the base of the boiler and one near the base of the chimney |
| D. | Two fans/blowers are installed both at the base of the boiler |
| Answer» D. Two fans/blowers are installed both at the base of the boiler | |
| 12. |
Where is fan/blower located in case of forced draught? |
| A. | Near the base of chimney |
| B. | At the top of the chimney |
| C. | At the grate |
| D. | At the base of the boiler |
| Answer» E. | |
| 13. |
In case of Induced draught, where is the fan/blower installed? |
| A. | Near the base of chimney |
| B. | At the top of the chimney |
| C. | At the grate |
| D. | At the base of the boiler |
| Answer» B. At the top of the chimney | |
| 14. |
Mechanical draught is used in locomotives and small installations. |
| A. | True |
| B. | False |
| Answer» C. | |