Thermodynamics (ME-302) - Important Questions

A piston-cylinder device contains 0.5 kg of nitrogen gas at 250 kPa and 300 K. The gas expands isothermally (pV = constant) to a final pressure of 100 kPa. Calculate the boundary work done by the gas during the process.

State the Kelvin-Planck and Clausius statements of the second law of thermodynamics.

Discuss the Clausius inequality and its role in defining the second law of thermodynamics.

A reversible heat engine receives 200 kJ heat from a source and drives a reversible refrigerator operating between an intermediate reservoir and a cold reservoir. Given the heat supplied to the engine and the net work output, find the heat absorbed by the refrigerator and the net heat rejected to the intermediate reservoir.

Explain heat and work transfer, distinguish between path and point functions with examples, and show why heat and work are path functions.

State the first law of thermodynamics for a closed system and apply the steady flow energy equation to a turbine, nozzle and compressor explaining each term.

What is the Carnot cycle? Derive the expression for its thermal efficiency and discuss its significance as a standard of comparison.

A rigid vessel of volume 0.86 m3 contains 1 kg of steam at a pressure of 2 bar. Using steam tables evaluate the specific volume, temperature, dryness fraction/quality, specific internal energy, specific enthalpy and specific entropy of steam.

Draw the T-s phase equilibrium diagram for water / pure substance showing wet region, dry saturated steam region and compressed liquid region with constant pressure, volume and dryness fraction lines.

Explain pure substance and its phases, formation of steam and its thermodynamic properties.

Explain with neat sketch the working of the combined separating and throttling calorimeter for determining dryness fraction, including the need for combined method and shortcomings of individual methods.

In an ideal constant-volume Otto cycle the pressure and temperature at the beginning of compression are 97 kN/m2 and 40 degC respectively. The compression ratio is 7:1 and heat supplied is 1200 kJ/kg. Find the thermal efficiency, maximum temperature, work output and mean effective pressure.

Derive the air-standard efficiencies of Otto, Diesel and Dual cycles and compare Carnot, Otto, Diesel and Dual cycles for the same compression ratio and heat addition.

Describe the internal energy, enthalpy and specific heat of gas mixtures and derive expressions for mixture properties in terms of mass and mole fractions.

Compare actual and theoretical combustion processes and discuss their effect on engine performance.

Explain the significance of enthalpy of formation and its relation to enthalpy of reaction in thermodynamic systems.