Thermodynamics Mechanical previous year questions with answer

Ques 21 GATE 2022 SET-1

The Clausius inequality holds good for?

Ques 22 GATE 2022 SET-1

A polytropic process is carried out from an initial pressure of 110 kPa and volume of 5 m³ to a final volume of 2.5 m³. The polytropic index is given by n = 1.2. The absolute value of the work done during the process is _______ kJ (round off to 2 decimal places).

Ques 23 GATE 2022 SET-1

In a steam power plant based on Rankine cycle, steam is initially expanded in a high-pressure turbine. The steam is then reheated in a reheater and finally expanded in a low-pressure turbine. The expansion work in the high-pressure turbine is 400 kJ/kg and in the low-pressure turbine is 850 kJ/kg, whereas the pump work is 15 kJ/kg. If the cycle efficiency is 32%, the heat rejected in the condenser is ________ kJ/kg (round off to 2 decimal places).

Ques 24 GATE 2022 SET-1

An engine running on an air standard Otto cycle has a displacement volume 250 cm³ and a clearance volume 35.7 cm³. The pressure and temperature at the beginning of the compression process are 100 kPa and 300 K, respectively. Heat transfer during constant-volume heat addition process is 800 kJ/kg.. The specific heat at constant volume is 0.718 kJ/kg.K and the ratio of specific heats at constant pressure and constant volume is 1.4. Assume the specific heats to remain constant during the cycle. The maximum pressure in the cycle is ______ kPa (round off to the nearest integer).

Ques 25 Gate 2021 Set-1

In the vicinity of the triple point, the equation of liquid-vapour boundary in the P – T phase diagram for ammonia is ln P= 24.38 - 3063/ T , where P is pressure (in Pa) and T is temperature (in K). Similarly, the solid-vapour boundary is given by ln P=27.92-3754 / T . The temperature at the triple point is _______K (round off to one decimal place).

Ques 26 Gate 2020 Set-2

If a reversed Carnot cycle operates between the temperature limits of 27°C and –3°C, then the ratio of the COP of a refrigerator to that of a heat pump (COP of refrigerator/ COP of heat pump) based on the cycle is __________ (round off to 2 decimal places).

Ques 27 Gate 2019 Set-1

During a non-flow thermodynamic process (1-2) executed by a perfect gas, the heat interaction is equal to the work interaction (Q_1-2 = W_1-2) when the process is

Ques 28 GATE 2017 SET-2

A mass m of a perfect gas at pressure p₁ and volume V₁ undergoes an isothermal process. The final pressure is p₂ and volume is V₂. The work done on the system is considered positive. If R is the gas constant and T is the temperature, then the work done in the process is

Ques 29 GATE 2017 SET-2

If a mass of moist air contained in a closed metallic vessel is heated, then its

Ques 30 GATE 2017 SET-2

In the Rankine cycle for a steam power plant the turbine entry and exit enthalpies are 2803 kJ/kg and 1800 kJ/kg, respectively. The enthalpies of water at pump entry and exit are 121 kJ/kg and 124 kJ/kg, respectively. The specific steam consumption (in kg/kW.h) of the cycle is ________.