GATE ME topic:thermodynamics PYQs & Answers

Questions 1–10 of 58. Imported answers require independent review unless marked reviewed.

For an ideal gas, starting from state point 1, two different process take place. The corresponding final states in these two processes are 2 and 3, lying on same isotherm. If

and

represent pressure and enthalpy, respectively, then which one of the following options is correct?

Your answerChoose one option.

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For the isothermal expansion of an ideal gas in a piston cylinder system, the net heat supplied during the process is equal to the net work. Which one of the following statements is correct for the given process?

Your answerChoose one option.

The process is possible.

The process is not possible as it violates the second law of thermodynamics.

The process is not possible as it violates the first law of thermodynamics.

The process is possible, however, it violates the second law of thermodynamics.

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A liquid comes out of the reactor of a chemical plant at 250 °C temperature with a flow rate of 100 LPM. The ambient temperature is 25 °C. Density and specific heat of the liquid remain constant at 1000 kg/m³ and 4.18 kJ/kg K, respectively, for the given range of temperature. The rate of energy associated with the hot liquid stream at the exit of the plant is ______ kW (rounded off to 2 decimal places).

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A rigid closed vertical cylindrical vessel of 15 cm diameter contains 5 kg water at 80 °C with 10% quality. The water is heated till its temperature reaches 130 °C. Considering only a horizontal separated interface between liquid and vapor, the dip in the liquid level after the heating process is ______ cm (rounded off to 2 decimal places).

Properties of water at various saturation temperatures are given in the table below.

Temperature	Specific volume		Specific internal energy
(°C)	(m³/kg)	(m³/kg)	(kJ/kg)	(kJ/kg)
80	0.001029	3.4053	334.97	2481.60
130	0.001070	0.6680	546.10	2539.50

, and

are temperature, specific volume, and specific internal energy, respectively. Subscripts

and

represent saturated liquid and saturated vapor, respectively.

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Air inside a rigid, thermally-insulated tank undergoes stirring as shown in the figure below. Which one of the following options is correct?

Diagram for Mechanical Engineering question 18

Your answerChoose one option.

The enthalpy of the air increases while the entropy of the air remains constant

Both the enthalpy and the entropy of the air remain constant

Both the enthalpy and the entropy of the air increase

The enthalpy of the air decreases while the entropy of the air increases

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A thermodynamically closed system contains 1 kg of hydrogen. The system undergoes a reversible polytropic process with polytropic index 1.3. The work output during the process is 400 kJ. During the process, hydrogen behaves as an ideal gas with constant specific heats. The absolute value of heat transfer during the process is __________ kJ (rounded off to 1 decimal place).

Specific heat of hydrogen at constant pressure = 14.56 kJ kg

Specific heat of hydrogen at constant volume = 10.4 kJ kg

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A furnace can supply heat steadily at 1200 K at a rate of 2400 kJ/min. The maximum amount of power (in kW) that can be produced by using the heat supplied by this furnace in an environment at 300 K is

Your answerChoose one option.

300

150

1800

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Consider an air-standard Brayton cycle with adiabatic compressor and turbine, and a regenerator, as shown in the figure. Air enters the compressor at 100 kPa and 300 K and exits the compressor at 600 kPa and 550 K. The air exits the combustion chamber at 1250 K and exits the adiabatic turbine at 100 kPa and 800 K. The exhaust air from the turbine is used to preheat the air in the regenerator. The exhaust air exits the regenerator (state 6) at 600 K. There is no pressure drop across the regenerator and the combustion chamber. Also, there is no heat loss from the regenerator to the surroundings. The ratio of specific heats at constant pressure and volume is

. The thermal efficiency of the cycle is ________ % (answer in integer).

Diagram for Mechanical Engineering question 45

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A piston-cylinder arrangement shown in the figure has a stop located 2 m above the base. The cylinder initially contains air at 140 kPa and 350 °C and the piston is at rest in equilibrium at a position which is 1 m above the stops. The system is now cooled to the ambient temperature of 25 °C. Consider air to be an ideal gas with a value of gas constant

kJ/(kg.K).

The absolute value of specific work done during the process is ______ kJ/kg (rounded off to 1 decimal place).

Diagram for Mechanical Engineering question 46

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A heat pump (H.P.) is driven by the work output of a heat engine (H.E.) as shown in the figure. The heat engine extracts 150 kJ of heat from the source at 1000 K. The heat pump absorbs heat from the ambient at 280 K and delivers heat to the room which is maintained at 300 K. Considering the combined system to be ideal, the total amount of heat delivered to the room together by the heat engine and heat pump is ______kJ (answer in integer).

Diagram for Mechanical Engineering question 47

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GATE ME topic:thermodynamics PYQs

How to practice topic:thermodynamics

Question 23

Question 28

Question 56

Question 57

Question 18

Question 54

Question 20

Question 45

Question 46

Question 47