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. |
Find out the temperature of outside air if a chimney 30 m high creates a draught of 25 m in terms of column if hot gases. The temperature of hot gases is 330°C. 18 kg of air is to be supplied for complete combustion of 1 kg of fuel. |
| A. | 38°C |
| B. | 28°C |
| C. | 25°C |
| D. | 32°C |
| Answer» B. 28°C | |
| 2. |
How much air is used per kg of coal burnt in a boiler having a chimney of height 32 m to create draught of 170 N/m2. The temperature of outside air is 25°C and hot gases inside chimney is 330°C. |
| A. | 10.16 kg of air per kg of coal burnt |
| B. | 12.00 kg of air per kg of coal burnt |
| C. | 14.32 kg of air per kg of coal burnt |
| D. | 19.25 kg of air per kg of coal burnt |
| Answer» B. 12.00 kg of air per kg of coal burnt | |
| 3. |
A 27 m high chimney produces a draught of 30 m in terms of Column of hot gases. The amount of air supplied for complete combustion of 1 kg of fuel is 20 kg. If the temperature of outside air is 27°C, determine the temperature of the hot gases inside the chimney. |
| A. | 456°C |
| B. | 392°C |
| C. | 423°C |
| D. | 398°C |
| Answer» C. 423°C | |
| 4. |
Find draught in terms of column of hot gases, if the temperature of hot gases inside the chimney is 350°C. The height of the chimney is 30 m. The temperature of outside air is 25°C. The air supplied for complete combustion of 1 kg of fuel is 20 kg. |
| A. | 29.73 m |
| B. | 32.46 m |
| C. | 45.32 m |
| D. | 30.25 m |
| Answer» B. 32.46 m | |
| 5. |
Find the temperature of the hot gases inside the chimney if the draught produced by a 25 m high chimney is 15 mm of water. The temperature of the air outside is 25°C and 18 kg of air is supplied for complete combustion of 1 kg of fuel. |
| A. | 298°C |
| B. | 330°C |
| C. | 456°C |
| D. | 364°C |
| Answer» E. | |
| 6. |
A chimney 30 m high produces a draught of 16 mm of water. The temperature of hot gases inside the chimney is 300°C. Calculate the temperature of outside air if 20 kg of air is supplied for complete combustion of 1 kg of fuel. |
| A. | 30°C |
| B. | 27°C |
| C. | 25°C |
| D. | 20°C |
| Answer» C. 25°C | |
| 7. |
A 28 m chimney is full of hot gases at temperature 300°C. The air supplied for complete combustion of 1 kg of coal is 18 kg. calculate draught in N/m2 if the temperature of outside air is 25°C. |
| A. | 140.32 N/m2 |
| B. | 187.54 N/m2 |
| C. | 150.32 N/m2 |
| D. | 146.76 N/m2 |
| Answer» E. | |
| 8. |
Calculate how much air is used per kg of coal burnt, if the chimney height is 35 m which creates a draught of 20 mm of water. The temperature of hot gases inside the chimney is 330°C and temperature of air outside is 27°C. |
| A. | 29.52 kg of air per kg of coal |
| B. | 21.34 kg of air per kg of coal |
| C. | 22.45 kg of air per kg of coal |
| D. | 19.54 kg of air per kg of coal |
| Answer» B. 21.34 kg of air per kg of coal | |
| 9. |
A chimney is 25 m high. The temperature of hot gases inside chimney is 300°C and temperature of air outside chimney is 30°C. If 20 kg of air is supplied to the furnace per kg of coal find the equivalent column of hot gases that would produce the same draught pressure. |
| A. | 20.02 m |
| B. | 22.40 m |
| C. | 24.42 m |
| D. | 22.60 m |
| Answer» B. 22.40 m | |
| 10. |
Calculate the draught in mm of water if the chimney height is 30 m, the temperatures of hot gases inside chimney and outside air are 330°C and 30°C respectively. Also, the furnace is supplied with 15 kg of air per kg of coal burnt. |
| A. | 14.67 mm of water |
| B. | 17.64 mm of water |
| C. | 16.22 mm of water |
| D. | 16.19 mm of water |
| Answer» D. 16.19 mm of water | |
| 11. |
Which of the following is the correct formula for calculating the pressure difference causing the gas flow through the combustion chamber?a) (ρa – ρg)gHb) (ρa + ρg)gHc) (ρg – ρa)gHd) (ρg + ρ |
| A. | (ρa – ρg)gH |
| B. | (ρa + ρg)gH |
| C. | (ρg – ρa)gH |
| D. | (ρg + ρa)gH |
| Answer» B. (ρa + ρg)gH | |
| 12. |
Natural draught is obtained using _____ |
| A. | Economizer |
| B. | Induced fan |
| C. | Chimney |
| D. | Induced and forced fan |
| Answer» D. Induced and forced fan | |
| 13. |
Artificial draught is classified into steam jet and mechanical draught. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 14. |
Draught is classified into _____ |
| A. | Artificial and natural draught |
| B. | Induced and forced draught |
| C. | Steam jet and mechanical draught |
| D. | Chimney draught and boiler draught |
| Answer» B. Induced and forced draught | |
| 15. |
What is draught? |
| A. | The condition of a dry boiler is called draught |
| B. | It’s a small pressure difference which causes the flow of gases |
| C. | It is a boiler mounting |
| D. | It is a boiler accessory |
| Answer» C. It is a boiler mounting | |