Thermodynamics Mechanical Gate Previous Year Questions

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).

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).

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

a) Isentropic
b) Polytropic
c) Isothermal
d) Adiabatic