Thermodynamics Mechanical previous year questions with answer

Ques 1 GATE 2025

Let a spherical block of ice at -7°C be exposed to atmospheric air at 30°C with the gravitational direction as shown in the figure below. What will be the overall direction of air flow in this situation?

Ques 2 GATE 2025

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

Ques 3 GATE 2025

In a psychrometric chart, one axis represents dry-bulb temperature. The axis, that is perpendicular to the dry-bulb temperature axis, represents

Ques 4 GATE 2025

The thermal efficiency of an ideal air-standard Otto cycle is 0.5. The value of specific heat ratio of air is 1.4. The compression ratio of the cycle is ______ (rounded off to 1 decimal place).

Ques 5 GATE 2025

A thermal power plant is running with no reheat or regeneration. The specific enthalpy and specific entropy of steam at the turbine inlet are 3344 kJ kg^-1 and 6.5 kJ kg^-1K^-1 respectively. The turbine isentropic efficiency is 0.9, and the mass flow rate of steam at the turbine inlet is 102 kg s^-1. The turbine power output is ______ MW (rounded off to 1 decimal place).
Properties of saturated liquid and saturated vapor at turbine exit pressure

Ques 6 GATE 2025

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^-1K^-1
Specific heat of hydrogen at constant volume =10.4 kJ kg^-1K^-1

Ques 7 GATE 2025

A heat pump, operating in reversed Carnot cycle, maintains a steady air temperature of 300 K inside an auditorium. The heat pump receives heat from the ambient air. The ambient air temperature is 280 K. Heat loss from the auditorium is 15 kW. The power consumption of the heat pump is ______ kW (rounded off to 2 decimal places).

Ques 8 GATE 2024

A furnace can supply heat steadily at 1200 K at a rate of 24000 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

Ques 9 GATE 2024

Which one of the following statements regarding a Rankine cycle is FALSE?

Ques 10 GATE 2024

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 c_p / c_v = 1.4. The thermal efficiency of the cycle is % __________. (answer in integer).