GATE XE topic:thermodynamic-cycles PYQs & Answers — Page 3

Questions 21–30 of 37. Imported answers require independent review unless marked reviewed.

A refrigerator working on a reversed Carnot cycle has a Coefficient of Performance (COP) of 4. If it works as a heat pump and consumes work input of 1 kW, the heating effect will be:

Your answerChoose one option.

1 kW

4 kW

5 kW

6 kW

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For a refrigeration cycle, the ratio of actual COP to the COP of a reversible refrigerator operating between the same temperature limits is 0.8. The condenser and evaporator temperatures are 5°C and −30°C, respectively. If the cooling capacity of the plant is 2.4 kW, then the power input to the refrigerator is: (COP: Coefficient of Performance)

Your answerChoose one option.

1.00 kW

1.33 kW

1.25 kW

2.08 kW

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An air-standard Diesel cycle with a compression ratio of 16 takes air at 1 bar and 300 K. If the maximum temperature in the cycle is 2100 K, then the thermal efficiency of the cycle is ______ % (1 decimal place). The ratio of the specific heat capacities of air is 1.4.

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The relation between the coefficient of performance of a refrigerator

and the coefficient of performance of a heat pump

Your answerChoose one option.

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An engine working on the air standard Diesel cycle has a compression ratio of 18. The cycle has a cut-off ratio of 1.7. If the ratio of specific heats of air is 1.4, then the thermal efficiency (in %) of the cycle (rounded off to 1 decimal place) is ________.

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An air standard Otto cycle has compression ratio of 4. The compression ratio of this cycle is changed to 6. If the ratio of specific heats is 1.4, the percentage increase in its thermal efficiency will be

Your answerChoose one option.

20.2

27.2

42.6

51.2

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The turbine inlet conditions of a Rankine cycle are 10 MPa and 500 °C, while the condenser pressure is 10 kPa. The enthalpy and entropy of saturated liquid at 10 kPa are 191.8 kJ/kg and 0.6492 kJ/kg.K, respectively, while the enthalpy and entropy of vaporization at 10 kPa are 2392.1 kJ/kg and 7.4996 kJ/kg.K, respectively. The enthalpy and entropy at the inlet to the turbine are 3375.1 kJ/kg and 6.995 kJ/kg.K, respectively. The condenser outlet has saturated liquid. Neglecting the pump work, the thermal efficiency (in %) of the cycle (rounded off to 1 decimal place) is ________.

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The minimum and maximum temperatures of an air standard Brayton cycle are 300 K and 1100 K, respectively. The pressure ratio of this cycle is 6. The ratio of specific heats is 1.4 and the specific heats are constant. For this cycle, the ratio of network output to the turbine work (rounded off to 2 decimal places) is ________.

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Addition of a reheat process to a simple Rankine cycle will always

Your answerChoose one option.

increase both efficiency and work output of the cycle.

increase efficiency but not necessarily work output of the cycle.

increase work output but not necessarily efficiency of the cycle.

decrease both efficiency and work output of the cycle.

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A Carnot cycle implemented using an ideal gas in a piston-cylinder system will have

Your answerChoose one option.

work transfer in two parts of the cycle and heat transfer in the other two parts of the cycle.

work transfer in all four parts of the cycle and heat transfer in two parts of the cycle.

work transfer in two parts of the cycle and heat transfer in all four parts of the cycle.

work transfer in all four parts of the cycle and heat transfer in all four parts of the cycle.

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GATE XE topic:thermodynamic-cycles PYQs

Question 1

Question 11

Question 22

Question 4

Question 9

Question 14

Question 20

Question 21

Question 4

Question 5