MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Thermodynamics Questions and Answers knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A car engine operates with a thermal efficiency of 35%. Assume the air-conditioner has a coefficient of performance of 3 working as a refrigerator cooling the inside using engine shaft work to drive it. How much fuel energy should be spend extra to remove 1 kJ from the inside? |
| A. | 0.752 kJ |
| B. | 0.952 kJ |
| C. | 0.852 kJ |
| D. | none of the mentioned |
| Answer» C. 0.852 kJ | |
| 2. |
In a cryogenic experiment you need to keep a container at -125°C although it gains 100 W due to heat transfer. What is the smallest motor you would need for a heat pump absorbing heat from the container and rejecting heat to the room at 20°C? |
| A. | 97.84 kW |
| B. | 98.84 kW |
| C. | 99.84 kW |
| D. | 95.84 kW |
| Answer» B. 98.84 kW | |
| 3. |
An air-conditioner provides 1 kg/s of air at 15°C cooled from outside atmospheric air at 35°C. Estimate the amount of power needed to operate the air-conditioner. |
| A. | 1.09 kW |
| B. | 1.19 kW |
| C. | 1.29 kW |
| D. | 1.39 kW |
| Answer» E. | |
| 4. |
A heat pump is used to meet the heating requirements of a house and maintain it at 20°C. On a day when the outdoor air temperature drops to 2°C, the house is estimated to lose heat at a rate of 80,000 kJ/h. If the heat pump under these conditions has a COP of 2.5, determine the rate at which heat is absorbed from the cold outdoor air. |
| A. | 32000 kJ/h |
| B. | 48000 kJ/h |
| C. | 54000 kJ/h |
| D. | 72000 kJ/h |
| Answer» C. 54000 kJ/h | |
| 5. |
A heat pump is used to meet the heating requirements of a house and maintain it at 20°C. On a day when the outdoor air temperature drops to 2°C, the house is estimated to lose heat at a rate of 80,000 kJ/h. If the heat pump under these conditions has a COP of 2.5, determine the power consumed by the heat pump. |
| A. | 32000 kJ/h |
| B. | 33000 kJ/h |
| C. | 34000 kJ/h |
| D. | 35000 kJ/h |
| Answer» B. 33000 kJ/h | |
| 6. |
The food compartment of a refrigerator is maintained at 4°C by removing heat from it at a rate of 360 kJ/min. If the required power input to the refrigerator is 2kW, determine the rate of heat rejection to the room that houses the refrigerator. |
| A. | 450 kJ/min |
| B. | 460 kJ/min |
| C. | 470 kJ/min |
| D. | 480 kJ/min |
| Answer» E. | |
| 7. |
The food compartment of a refrigerator is maintained at 4°C by removing heat from it at a rate of 360 kJ/min. If the required power input to the refrigerator is 2kW, determine the coefficient of performance of the refrigerator. |
| A. | 4 |
| B. | 3 |
| C. | 2 |
| D. | 1 |
| Answer» C. 2 | |
| 8. |
A car engine with a power output of 50 kW has a thermal efficiency of 24 percent. Determine the fuel consumption rate of this car if the fuel has a heating value of 44,000 kJ/kg . |
| A. | 0.00273 kg/s |
| B. | 0.00373 kg/s |
| C. | 0.00473 kg/s |
| D. | 0.00573 kg/s |
| Answer» D. 0.00573 kg/s | |
| 9. |
Heat is transferred to a heat engine from a furnace at a rate of 80 MW. If the rate of waste heat rejection to a nearby river is 50 MW, determine the thermal efficiency for this heat engine. |
| A. | 47.5 % |
| B. | 27.5 % |
| C. | 37.5 % |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 10. |
Heat is transferred to a heat engine from a furnace at a rate of 80 MW. If the rate of waste heat rejection to a nearby river is 50 MW, determine the net power output for this heat engine. |
| A. | 30 MW |
| B. | 40 MW |
| C. | 50 MW |
| D. | 60 MW |
| Answer» B. 40 MW | |